RE: Rear derailer refuses to travel from top to low gear
Just wanted to let you know that I found the problem, thanks to your help.
Firstly, I had a look at those online tutorials, thanks CNY-man. Finally started to make some sense about the derailers, and as I thought, there's not much to them at all. Gotta work on getting those clicks/gear changes back in the right spots, now, which should be good practice.
Now, on to the problem... you wouldnt believe it (or maybe you will!)
Well, looked at the derailer drop arm as you suggested, and it looked as straight as the day it was made. So no problem there. So inspected the cable all the way through the bike, which still looks new even tho I changed it about a year ago. Again no problem. So I moved up to the changer, pulled off the cover, and lo and behold... what do i find?
It seems that the cable end had managed to jump out of the recess where it usually sits, and had managed to crawl around the front of the cable retaining assembly. That little piece of led was then striking the changer case as it was moving through the ranges, but it was only doing it at the extremes of the range. So... I pulled it gently with a long nose plier and sat it back where it's supposed to be, re-assembled everything and whammo, everything was hunky dory. Had to adjust the tension on the cable as my attempts to find the problem yesterday had put that out of whack, but as you know, that's such a small job. And the bike is up and running again.
So thank you both for giving me the ideas you did. Simple as it was, it had me beat. The only mystery now is how the cable end jumped out of its seat in the first place. I noticed it after I had disassembled the bike to load it in the back of the car and I think something must have happened to loosen the cable up, perhaps when I was removing the wheel from the bike, and for some strange reason, it decided to live outside its usual home.
again thanks for helping. It wasnt such a difficult problem after all, but I was so baffled by the mystery that your calm advice helped to get my brain into gear.
so, thanks again.