.......another solution if the rubberbelt needs to be replaced: get any old CDROM drive out of a junkyard computer, open it up and look for the motor and the belt that drives the cd tray - there is usually only one. Get it out and transplant it to the 521i. The steps are: get the cd tray into open position, unplug the player, open the housing (5 screws), push two small lids close to front panel left and right to the cd tray and you can pull the tray out a little bit further, use a screwdriver to press down the cover over the belt-drive, lift it a little bit, remove the old belt and put the new one in, push the cover back into place, push the cd tray back into position and close the housing again.......done. Works great with mine and is done in less than 30 min!