RD53 failure modes

Hello, definitely you should be able to fix it. This kind of problem is caused by the missing thickness of the rubber stoppers of the positioner, which became goo in the years. You have two ways to solve this problem. First of all, remove the disk top cover plate in clean room, locate the positioner and note that is full of black goo. Remove it at best with isopropyl alcohol, sticks, paper, whatever, but be SURE not to spurt / touch on the disk surface. After this: - method 1, easier: locate two screws at the sides of the positioner coil which hold on position left and right stoppers. You should loosen the left one (head on the center of the disk) and move just slightly to the right, then tight the screw again. As you must repeat some times to find the right position, my advice is to have a PSU connected to the disk, and try before really tightening the screw if it is enough / too much / good. In this way you compensate for the thickness of the missing rubber stopper, but the head will receive some more shocks at start and during operations. -method 2: you will replace the missing rubber with a new one. You should find a piece of rubber sheet, thickness around 1mm. You cut a small chunk and somehow glue it to the stoppers again. Of course you need to clean it very well before, otherwise glue will not adhere. Let me know if you manage to fix it. Andrea