My son was formerly a sewing machine mechanic (14 years at that), and has fixed a few having the speed problem (for free), but he is no longer a sewing machine mechanic (except for me lol!). The motors do get dirty, and oil that has hardened can create all kinds of problems. I observed when he took my 201-2 apart and re-wired it -- of course, the 201 was notorious for not having the best wiring -- some wiring will hold up to age, some just doesn't. If you moved the wire on mine, you could hear it cracking and creaking -- my son wouldn't even plug it in before he rewired it.