The guts of the failed SRAM X.9 rear shifter from my Tour Easy:
The identical rear shifter on Mary’s bike also seems to be wearing out, as it glides between two of her favorite click stops a bit too easily. You can see the spring peeking out to the right, beyond the white tube, and the notches forming the clicks.
AFAICT, the raised section between the notches is wearing down; there’s no repair for that sort of thing. I took this one apart to see what’s inside: now we know!
We’ve agreed to not replace the shifter until the situation gets worse. An X.0 shifter should arrive shortly; it appears identical except for deeper scallops around the grip.