my bike rollers are making this awful screeching sound. its coming from the band that connects the front roller to the back. the back roller isn't gripping the band and the band (and front roller) stay put while the back one spins and screeches. how do i fix this? new band? i bought this minoura unit from someone on craigslist.

Kind of sounds like it might be an issue with the rear roller not rolling as freely as it should? Maybe check the bearings/preload on all of the rollers?