Hard to tell, so far. When the plastic pulley split the machine became unusable, so fixing for less than $10 seems worthwhile. If I get another thirty years out of it, that's a a bargin. I got worried enough about the setscrew grip to grind a pair of divots in the shaft. Doubtless that'll help some, but the aluminum is quite soft and the screws have a mushy feel I don't really like. The more I think about it the more mysterious the assembly sequence becomes. Physically it's identical to a large model airplane engine. The cylinder and crankcase are one piece, it looks impossible to dismantle non-destructively.
The photos are still at
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anybody's game to hazard a guess.
Thanks for everybody's attention and thoughts!
bob prohaska