Originally Posted by
fishboat
Brake fluid can be hard on some paints.
With a bike in that condition, I'm sure the shifter is fine. Spray it internally with WD40, work it through the range of gears(helps if you remove the chain so you can just click through the range), spray again, work it through the range, spray, work, spray, work..it'll loosen up and be fine. Finish it off with a light spray lube(machine-type oil) and you good to go. A minor tune up like this on the shifter that works is a good idea too.
Brake cleaner isn't brake fluid... it's a solvent in a spray can that evaporates rapidly and leaves no residue, and is safe on rubber... I've not come across one that damages paint yet, though it does take wax off..
WD40 is just another solvent, distillate that's less volatile and leaves a residue for a while. Personally I prefer to get the old grease right out, and start with new.