I'm sure there are guides/manuals, but honestly I've never looked. Sure someone has them handy otherwise I can look when I'm on the computer rather than phone.

I use a standard rheostat for a ceiling fan.

I always check, but they should come properly seated. And really no harm, there will be a bit more arcing than normal until the brushes wear to the correct shape and a lot more carbon dust in the filter... but unless you ran that vac at full power for hours and hours under extreme stress, real damage is very unlikely.

pitting of the commutator can and will occur from excessive arcing from the brushes. It's amazing how the same current applied differently can have such different results. However, it does take rather a good bit of time and with no load on the motor the arcing is substantially reduced. It is best to seat them properly with a stone and then fine tune at 50% voltage. Makes the difference between a 5 year motor life and a 50 year motor life.

D-T,

If you have the model # handy I can attempt to find you the exact documents for that motor.

Motor....

Well shoot, Ametek is not very friendly. I can find schematics, but more detailed instructions require the purchase of the entire service library and it's rather $$. Here is the schematic for the 115923. Basically you remove the fan shroud (usually 3-4 screws or bolts/nuts hold it to the mount) and then secure the armature and remove the retaining nut and the fans slide right off. I got to practice my first disassembly on a completely rusted/seized motor that I didn't care about salvaging so once I broke it apart, it was obvious how it was all connected and then I just jumped into the next one.