Hi. I have never had one fail in these, but on most dot matrix printers, you need to remove the side plate, and remove the belt from the gears, then at the clutch end up where the takeup reel sits. If it is the type that doesn't have a side plate, then look for screws that will allow the whole printer to swing open in halves. It really is different for each model of printer, so until I do one of them, I can't be specific. One rule I use, is that I take a screw half out, and wiggle the parts it is holding. If it looks like they have nothing to do with the area you are working with, screw it back up.
Hope this helps,
Mark
Mark, August 2008