This problem I'm starting to see on older TVs and Monitors. It is that the rubber wedges that are used to center the yoke in the correct position. What happens over time only on some brands is that rubber starts to react with varnish covering the yoxe windings. If nothing is done it will eventually eat throw the varnish destroying the windings in the yoxe. I had this happento me many years ago on a Montgomery Ward set from 1987( thread should still be available) the seat was OEM by sharp. Once I took the yoke off there was bunch of green corrosion were the rubber wedges touched the yoke. I don't know how common this but I think you all should be away of this as now as time goes this will be death of many seats unless the rubber wedges are removed and left out if that is possible to do or find a way to replace them. As I have seen the Commodore 1084 have seen fail in this way too. Hope this helps you be more aware of this porblem.