Good question about parts machines. So far I've only bought one for parts. A Singer 27 treadle. Mostly I bought it for the treadle parts because I have two other treadle machines that need them and the woodwork was trashed. The head of the machine I robbed of some tension parts to get my other 27 going but I also plan to buy new parts for the head and convert it to a hand crank machine.
I also have a 99 that I just robbed the needlebar out of it to get my daughter's 99k going. I plan to eventually replace the parts I used and make it a runner though I know it makes more sense to leave it as a parts machine.
My problem is I buy machines that probably should be parts machines then go ahead and fix them up anyway. I have a White that should be a parts machine. I paid $5 for it and as a parts machine I can get that back out of it easily. It will probably cost me another $20 to $30 to make it decent again. I plan to make it run again though financially it makes more sense not to.
I think I'm starting to see a pattern here.
Rodney