My shimano revo shift (model# RS-41) 7sp shifter has 7 "clicks" - that is, it has 7 positions it will shift to. Somehow, the numbers got misaligned with the clicks so that I can shift 1 gear above 1 but will not shift down to 7. I have tried forcing the number ring back into alignment to no avail. It seems to be stubbornly attached to the twist mechanism.
It doesn't look like I can replace the shifter, either. From the looks of it, the shifter must slide off the handlebar (i.e. it will not separate into two pieces). However, my bike came with a rather "tacky" grip that will not budge and would be impossible to slide back on.
Even if I could replace it, I cannot find anywhere to buy a replacement shifter of this type.
I assume you're talking about a grip shifter. It sounds the cable has stretched. You need to tighten the cable at the barrel adjuster. This is located where the cable leaves the cable housing at the derailure. There might also be one on your shifter. If you don't have a barel adjuster, you need to losten the bolt attaching to the cable and take up slack in the cable.
Well, the problem is with the shifter, in that it physically won't shift to 7. I get to 6, and it won't click to 7 unless I exert a large amount of force on it. Similarly, it will click and lock in a position above 1. I have tried adjusting the cable but the shifter still exhibits the same behavior. I suppose I could just set it up so that the bike is in gear n+1 when the shifter shows I am in gear n but that wouldn't be a very elegant solution.