It is a consumer unit. Not likely to last years and years with commercial use. Maybe try it. If it lasts long enough, trash it when it dies and get another.
My GUESS is something, likely dried soap or some other foreign material, was jarred loose and plugged up the canon. There are posts and videos on how to take the canon apart and clean it.
I also use a 4-post lift...HUGE help being able to raise car to height desired. I also use a mechanics seat on large wheel casters to lessen the time spent on my feet. Also a "Swifter" with...
100 psi might be a bit low...but I TOTALLY agree about not aiming a pressure washer at hands, feet, whatever... Injection wounds can be very serious. Many people get away with using the pressure...
I agree with hogie. With a coating, if you decide to correct any trail rash, you'd have to polish through the coating. If you use wax, a strip wash will be all that is needed.
The nozzle could be the entire cause of what you are experiencing. The video Supra9497 linked is a classic demonstration of "sheet rinsing" aka "pool rinsing" aka...