Here are a few pictures of the Shop Vac motor I mentioned in the second post.
It isn't meant to be taken apart but you can see that one brush never moved from new and the other went down until it couldn't anymore and the motor then cooked.
The picture below shows the end of the motor and you can see in the upper brush that it no longer shows in the pair of slots on the upper brush where it does show in the lower.
Below is the lower brush that also shows the carbon brush in the little half-moon cutout just above the armature. It never moved from new.
This picture shows the upper brush that was doing all the work and it barely shows in the half-moon cutout. Bad picture, you'll have to take my word for it. The top of the brush and spring are visible in it. There is about 7 or 8mm of brush left where the other side is close to 30mm.
A motor will run on one brush, likely not as efficiently, until it can't make good contact and then it all grinds to a halt.
A good motor can probably be taken apart and fixed but this thing was never meant to be repaired so the vacuum became a scrap wood bin on wheels, the rest went to the scrap metal pile and the dumpster at the transfer station. I kept the motor as I bought another of the same and will check it soon to see if the brushes are wearing evenly and if not free them up and replace the shorter with the one from this motor.
Pete
