For the gearing… change all the cable and (sleeve ?).
If you have "push push "-STI system, change for "thumbshifter". The STI system has never work…
I changed the inner and outer cable, and made the bottom loop a bit larger, it doesn't look as good as the original loop (that was tighter) but the shifting has really improved.
It's still not good compared to a push-pull system, but I'm gonna leave it like this. It's something different, and like with Italian Motorbikes, I'm gonna say it has character.
When my Yamaha has something like this it's a problem, when a Ducati has it, it's character
'98? American Eagle Lake Tahoe
'91 Cannondale SM800 (Beast of the East)
'93 Marin Bear Valley SE
'04 Yamaha XT660R