I have a very puzzling problem with the front mechanical disc brakes on a big-box retailer mountain bike. Nothing fancy, and it used to work well for over a year but since I last dismantled it to clean it and eliminate squeal it's never quite worked properly.
Problem seems to be too much lever travel; when pulled tight I can get effective braking but released fully the brakes still stick. Letting out a bit more cable from the clamp will allow the wheel to spin freely on release but the brakes are almost useless even at max.
I've tried tightening and loosening the bolt in the caliper center but this doesn't seem to change anything (what does it do anyway?). Can someone advise how I can reduce the "range" of mechanical disk brakes or otherwise resolve this issue?