Popping into 2nd from 3rd gear - '78 KZ1000 B2

Hey guys,

Pretty much as the subject describes- my KZ1000 will drop into 2nd from 3rd gear while cruising at moderate "in-town" speeds. All other gears are fine. It shifts fine up and down through all 5 gears. I'm not well versed on the drivetrain so any ideas are welcome.

check the shifter linkage /lobster claw under output shaft cover and trap door,maybe spring going bad?

I will definitely check that out. I'm curious though, if that was the issue would it not cause the problem between all gears?

*Bump

Just wondering if anyone else might have any ideas for my bike's issue. I'm probably going to start looking at it this weekend so thought it'd be good to have 2 or 3 possible things to check out. Thanks!