So I took my shifter out today to replace the seat. When I removed the shifter, I didn't even really find any remnants of the old seat. Maybe some tiny fragments, but that's it. There was just an o-ring in the place where the seat should be. Is that supposed to be there? Should I just remove it and put the new seat in? Any help is appreciated.

 

Same here. The old one was vanished. The old style had a rubber part (like an O-ring sort of) and a plastic part, the plastic part brittles and dies.

The new style was one piece and is a better material.

 

Okay. After I posted, I went back out to the shop, and the shifter wouldn't lock in with both the o-ring and seat in there, so I took out the o-ring and put just the new seat in, and it worked fine. Shifts MUCH better now. Thanks.