Flex 3401 Burnt Out (HELP)

[Kaban]

Brushes are cheap. Replace those first.

We have several Flex at the shop. Changed the brushes over a dozen times over the years on them. I've seen various symptoms before the machines died. Sometimes the machine would just go from 100% to not working at all. Other times, the trigger would act as if it had a mind of its own, slow to change speeds, slow to react to input, etc. So far, replacing the brushes fixed all the problems. The only other issues we've had was having to replace some cords, but that's probably due to us using them very aggressively.

[MarkD51]

Mark, thanks a bunch for your information! Will be ordering a switch asap!

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Just trying to help, and I hope my guess is correct. I'm surely no authority on Flex Tools specifically, don't even own a Flex .
Others here may also be of better help, and have much better experience than I with this particular machine.

I hope it will not also be another part associated with the switch, called the Speed Controller, which is a much more expensive part. If only just the switch-trigger is bad, and this less expensive part does the trick, then I'd say you got lucky and saved some money. (Was there any prior issues of speed control with the machine?)

In this other thread, I had noted some mention a cost of $120-$130, and I might guess that this was the switch-controller cost combined, or perhaps I'm wrong, that this was the cost of the Switch and the labor to install it? Again, hope it is not that more expensive part.

[P3 S197]

Just trying to help, and I hope my guess is correct. I'm surely no authority on Flex Tools specifically, don't even own a Flex .
Others here may also be of better help, and have much better experience than I with this particular machine.

I hope it will not also be another part associated with the switch, called the Speed Controller, which is a much more expensive part. If only just the switch-trigger is bad, and this less expensive part does the trick, then I'd say you got lucky and saved some money. (Was there any prior issues of speed control with the machine?)

In this other thread, I had noted some mention a cost of $120-$130, and I might guess that this was the switch-controller cost combined, or perhaps I'm wrong, that this was the cost of the Switch and the labor to install it? Again, hope it is not that more expensive part.

Went ahead and ordered a switch and brushes. Never had any trouble with the speed selector on the beast. Only the trigger acting like it was possessed. Gonna pull her apart today or tomorrow and do a visual inspection. Hoping for the best.

Thanks to everyone for the replies! Will bring pictures and details from the repair once the parts arrive.



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[MarkD51]

[QUOTE=P3 S197;1654237]Went ahead and ordered a switch and brushes. Never had any trouble with the speed selector on the beast. Only the trigger acting like it was possessed. Gonna pull her apart today or tomorrow and do a visual inspection. Hoping for the best.

Thanks to everyone for the replies! Will bring pictures and details from the repair once the parts arrive.
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Sounds like a plan. Might be a good idea to take some snap shots of the disassembly steps to aid you, and perhaps be of help for re-assembly.

A spare set of brushes is always a good thing to have on hand if you need them. Might be a good idea then to inspect the original brushes when the new ones come, if the originals look good, maybe just simply blow the cavities out with some canned air prior to re-installation of that set, or whichever you choose to then use.

I've been fortunate to save a few costly tools of mine by simply ordering the parts and doing the repairs. myself.

Please do keep us all posted on your findings and outcome.

[MarkD51]

Not trying to string this thread out to be too long, but what I likely would've done first was to open up the tool first and inspect. This might have guided you to help find the specific problem, and as others have mentioned, the possibility of a bad Brush-Brushes, a Power Cord or Cord Connection, and other Parts that might be the culprit other than the Trigger itself?

There is a specific Sub-Section for Flex Polishers, and perhaps best that such info would be contained in one specific sub section area so that others may find such information valuable within that sub-section. Thus, if the moderators wish to move this thread, we'll all find it by search.

I hope the moderators of this group hasn't minded my suggestions of a fix, nor links to outside parts suppliers for the Flex 3401 Tool.

One example of a tool fix I did a few years back, was breaking a Dremel Tool.
I was installing an additional Deadbolt Lock to an entrance door, and like a dummy bought the wrong size Hole Saw to cut the new hole. (1/8" too small, ugh!)

So, I said, no problem, I'll whip out my trusty Dremel and go to work slightly enlarging the Hole. It was a Metal Laminate Door, and it was a little bit too much for the Dremel, I burned it up, or thought I did, as the Motor ran, but the Chuck remained stationary.

I had to finish the job with a half-round File.

I was sort of sick of what originally cost me about $100 for that Dremel Tool Kit, and smartly decided to open it up and see what went wrong inside?

Here, between the Motor and the Chuck-Collet was about a 2" long Plastic Splined Sleeve-Tube that connected the Drive Motor and Collet together, acting sort of like a little "Drive'Shaft". It shattered due to age and stress, thus breaking the mechanical connection.

Through a diligent search, I was able to find a parts supplier online who carried the specific part for that specific model, the Plastic Sleeve was $11 and $5 to ship. Was a lot better than having to go out and buy another Dremel Tool!

[P3 S197]

Kept you waiting huh? The Beast is back! The switch was bad, no visible signs of burning despite the smell.

Big thanks to everyone, and special thanks to Brian at Apex Detail for his in depth YouTube video on the 3401! Definitely go watch it!

Here are a few pictures of the process.

1. Remove the 3 torx T10 screws from the handle.

2. Remove the single T10 screw holding the main power cord clamp.

3. The switch just lifts right up, it is completely plug and play. Just hold the new and old switch side by side and change the wires one at a time so you don't make any mistakes.

4. Place the switch inside the small notches in picture 5. This ensures the switch is centered. Make sure no wires will be pinched where the handle goes together.

5. Replace power cord clamp and reattach handle then you're done! Its really that easy!

I also decided to replace the gearbox grease with some EP2 Lithium grease while i was at it. The factory grease had minor contamination from the gears wearing, hence the greyish color in with the yellow.

Here's to many more years of faithful service from the old beast!




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[MarkD51]

So my guess was right?

[PaulMys]

You were right, Mark.

That was my guess as well, but you explained it so well I didn't bother posting.

Great post by the OP. Many think that these power tools are somehow hard to diagnose/fix for yourself. They most certainly are not.

Sure, there are some issues that a few will be lost to fix, but 90% of the time, it's a brush/cord/trigger issue. Easily fixed by even the most mildly mechanically inclined person.

[spazzz]

First person to say, did you replace the brushes while you were in there?

[VISITOR]

glad to see you're back in business!