I found that if the knurled adjustment knob is tightened, you get the behavior you described (front roller can be pushed back, but won't release). I found that if I loosened the knurled adjustment knob, the front roller doesn't get stuck. In fact, it seems like the adjustment knob serves to lock the front roller in the pushed back position. That is, to change the belt, I loosen the knurled knob, push back the front roller, then tighten the knurled knob to lock it in place. I slip off the old belt, slip on the new, then while pushing back again on the front roller, I unscrew the knurled adjustment knob so that the roller will release back into the normal operating position. I push the front roller using the method described above (pushing down on the whole unit while in the vertical position, front roller down, at the edge of a bench). The same knurled knob centers the belt. You center the belt by running the unit upside down (a little at a time at first) and adjusting the knurled knob until the belt is centered and stable. I picked mine up at a garage sale (old auto mechanic who died). Seems like a really hefty industrial strength beast, but I haven't put it through its paces yet.