Anyway, not to be disheartened, on further inspection there are three teeth in mesh with the mating gear, so although not perfect, it will suffice for now until I can find a replacement part, I don’t need yet another “pending” thing in my growing pile..
Down to the heart of the matter and the ever increasing stench of rotten eggs 
The only thing I can think of is that someone has used an organic type lube that has gone rotten?? Maybe whale oil?
I also see signs of damage to the arbor pivot hole as the small spacer bushing is worn Hmm, where are those bits of metal?
Look at those nice dirty wheels/gears begging me to bring out their best side.
I know that in watch terminology that the correct denominator is “wheel” BUT my background is industrial maintenance and frankly, I have a very hard time calling these gears, wheels. Wheels do not have teeth and are not part of a gear train. After all, if these were wheels, they would simply turn and nothing would happen 😆
