I'm about to rebuild or have rebuilt my R/H Campy Chorus 10 spd shifter. The G-spring is apparently shot after about 5700 miles. Actually, this isn't a surprise considering Branford indicates that 10K-15K miles is normal and I shift the RD much more than I would on a single - at least 2X. The likely parts, G-spring and a few other bits are not expensive, but don't be surprised if you start experiencing shifting problems earlier than expected. My symptom is a weak shift up from my 11t cog, sometimes not shifting sometimes double shifting; this is apparently classic for a weak G-spring. Wouldn't trade these shifters, however, as I think the ergonomics are really right for a tandem.