I would take the measurements of the bearings and order them from a bearing supply online or through a local hard ware store. Where did you end up having a bad bearing? Tuning the cassette is not an easy task, if thats where its at you might be better off calling Tormate's tech department.
Not sure which bearing is bad yet but it makes a screaching sound when I move the gantry in some spots. So I think it's time to replace and clean a lot of the bearings. The cassette seems ok.
