Working on an old Diamondback Ascent II. I do not have the bike with me, but I do know that it is Shimano 7 speed. The rear shifter has very little tension on the thumb lever. The shifting is adjusted perfectly but the lever only works if you ease into it very slowly, otherwise it just moves freely. I figured I'd just get a new shifter. Does anyone know what type it uses? Do I need a shifter/brake combo like the Acera system or can I just replace the shifter? I need something real cheap so I don't care if it doesn't match. It can be SRAM twist shifter. Doesn't matter. BTW, this is a bike I'm working on for someone else and he just wants something that works.