Originally Posted by
blamester
Hard to diagnose with out more detailed info.
But it could just be that uniglide or twist tooth doesn't work as good as modern chains and cassettes. So if you are used to modern shifting the 600 may seem to be working badly when it is actually working normally.
I've never used modern shifting, is early-mid 80's that much worse?
I have the 105 1050 set which I'm using on friction, and it shifts good. If it's just the larger cogs, maybe loosen the limit screw or the B-screw? The largest cog should be no more than 28 I would think.