Went to play a tune just now and the platter started rotating really fast and not at a constant speed, works fine when quartz lock is on so Im thinking it might be the pitch slider or one of the connections to it. Ive had it happen before and the problem just seemed to disappear the second time I had a look at it, bit annoying.
Use the strobe dots to check the rotation is consistent.
Yeah they were pretty much there when I did the second post but it seemed a little fidgety compared to one of the others, really minor though it doesnt seem to be audible although I cant find a test tone to check it properly.