Trouble with third gear

Here is one for you....I am using a bug transmission with a cable shifter
tin my Beck Spyder hat has worked really well. Recently, however, I has
been getting more difficult going from second to third. A few times I could
not finesse it in at all. I have to rev high and shift from second to third
rapidly, not hard, rapidly. It downshifts great from fourth to third
however. All other gears work well.

Any ideas. If it was the syncro it should still go in if I match rpm with
speed, and it would make a difference downshifting to third also I would
think/

Questions? Answers?

it is a swing axel by the way. Clutch is excellent, etc.


Thanks,
Joe Gliebe