My daughter was just given a road bike with rx100 8speed components on it. Every thing works great except the front shifter. It moves smoothly but will not click and stay on the large chain ring. It looks like it has hardly been used but one never knows. Any ideas on the problem? I have a feeling I already know the answer but wanted to check on fixes before I looked for a replacement.
If you're lucky and it really is a shifter with very few miles on it, the factory lube inside it may just be stiff.
Do you have access to compressed air? If so, spray WD40 inside the shifter "blade" (the parts assembly attached to the brake lever part of the unit) then blast compressed air through it. Repeat this 3 or 4 times. If the shifter's problems aren't a result of mileage and wear you should see an improvement.