Hello, I just purchased a 1991 Trek 6000 with Suntour Xpress accushifters and Suntour XC LTD derailleurs. I am having a hell of a time dialing in the rear derailleur. The problem is, after tightening the derailleur cable, I can get it to shift from 7th to 1st by tightening the barrel adjuster quite a bit, but it wont shift from 1st to 7th w/o me loosening the barrel adjuster quite a bit. There is no happy median. The limit screws are set correctly and the hanger is aligned and visually the derailleur appears in good shape. The shifter cable was replaced. The shifters were gummed up but I was able to free them up and it is indexing correctly. If the problem is the shifter, what shifter should I use as a replacement, as I believe it has to be Suntour compatable? Any suggestions are appreciated. Thank you