Replacing belt in VC330 for friend. Stripped it all down - removed motor
assembly.

Problem: I noticed that the base plate assembly "wheel" - which connects to the
motor with the drive belt will not turn easily by hand. I say "wheel" because
it is not just that, it is an assembly with part of it being the drive wheel,
No way to strip down further.

I am not sure what that assembly is - or what is its purpose? It has a patent
number on it - but no more as far as I can see.

My question: what is it - and should the belt drive wheel on it rotate quite
freely.