Anyone know if a 7 gear rear indexed shifter, Shimano ST-CT15 is worth trying to recondition? Is it possible, given that there are likely warn plastic parts inside? Is there a compatible shifter I could replace this with that will work well with the Altus A20 rear derailler? The bike is not worth anything but the thumb shifter has gone loose and I'd hate to have to replace the whole assembly, possibly junking the bike in favor of a new one if I can't figure out a budget way to fix this.

Also, if anyone know, can I safely take the rear shifter assembly apart by releasing the top and bottom screw on the housing to inspect inside? The thing sort of still works but it keeps failing to down-shift regularly. The problem is not on the derailler as far as I can determine as I've adjusted the cable (and tested the cable tensioning somewhat) and when the shifter does work, the derailler appears to work pretty well...it appears to me to definitely be something wrong with the index assembly somewhere. (I had a similar problem with the front gearing where the 3 gear shifter wore out and I replaced it...uh, is there a more modern shifter I could adapt the A20 rear derailler with?)

I've kept this bike limping along for years--it was left by a bicycle thief 8 years ago in place of a much better bike that was stolen from a friend of mine, has been to Burning Man three times, etc-- and even managed to pick up a free compatible, much less heavily used, brake assembly last year from the REI bike shop guys.

What I liked at first about this bike was that no one would want to steal it, right? Plus, now that I know the bike pretty much inside and out (I've repeaked the bearings, etc), I don't want to give it up without a fight...just want to know what I'm facing with the worn out shifter.