I have made some progress. I'm learning more than really fixing anything though. I de-tensioned the rear curtain spring by half a turn and that seems to have helped. I can still see one side of the frame is a little under exposed though. I will most likely de-tension the rear curtain spring another half turn and test again. I also think the front curtain has been over tensioned, winding seems a bit stiffer than my others. I read where starting tension on these springs should be 5 turns for the front curtain and three for the rear. I almost want to just release the springs and start from scratch so I know exactly where I am on them. I wish there was an easy way to really test the shutter speed accuracy and timing.
I haven't committed to a full disassembly and CLA yet but I did put a drop of Break Free CLP oil at a few key points to see if it would help. It did seem to make the slow speeds much more reliable. They work correctly most of the time now. I did not have a single problem with the slow speeds yesterday...... Keeping that broken Zorki-4 was the best $15 I could have spent though. I have been able to learn and test on it before I do anything to my good ones.