Are you asking the symptoms of a failing motherboard? In my case, a 1985ish Elna, it started sewing slower and slower. Then sometimes it would quit altogether. It also started loosing features, like always ending with the needle up. I would try again after letting the machine "rest", and it would stitch for a bit. Now it doesn't start at all.
Or, are you asking if it is reparable. In my case, no. I've asked 4 different repairmen, and received the same answer. One suggested sending it to a place in either North or South Carolina, but that seems pretty expensive when there is no guarantee that a repair would be successful.