I had a similar issue where it would go into "safeguard mode", and I too was experiencing tape jams. Trouble with this model is that the tape rack is particularly malleable, being thin aluminum, so check to make sure that no major damage has been inflicted to the tape carriage. If it is partially bent out of shape, it can be easily bent back, just be gentle with it, and test just inserting a tape into the carriage over and over again, closing, reopening, all that, until it works fine. The effort to make a lighter camera backfired horribly in this case, it seems.

I just removed the tape(I find uot that the tape had jammed) cleaned the head with a cleaning tape and it works. Try that way and hoppelly that will work for you.

I have the same problem since today. Probably HEAD problems. I now have cleaned the heads with a cleaning cassette. Hopefully this solves the problem, at least the error message is gone now. I hope it will not return.