GG-1,
Unfortunately, you don't have much of a description for us for us for what is actually happening with the e-unit when you try to cycle it. It could be a lot of things (including all of the above).
As yours is a rather sudden malfunction, here's another possible (one that happened to me just as suddenly). I had bought a PW diesel that hadn't been run in quite awhile and was working on it to get it running again. All seemed well with it when I finished the process (or so I thought) when suddenly the e-unit wouldn't cycle. Apparently, the tabs on the ends of the drum sheared off and that effectively stopped it from rotating.
Roger
