I seem to remember having a similar problem with my SO76, I fixed it by pulling the reels that keep running, and compared the switch action to reels that were nearby and working properly, was able to find a difference with a couple switches gapped to close etc. and correct it. You can pull them out easy without disconnecting any wires and cycle them manually through the numbers and back to zero. They pop back in pretty easily.
Could be something else but worth taking a look IMO

If the targets reset all the way up, but some don't fall all the way down, it might be the springs are a bit too loose for those targets.
Not sure if I understand what you mean though. The reset bar should actuate evenly across the bank. It can't really go up on one side and not the other as it is a solid reset bar all the way across. Try actuating the mechanism by pushing the reset coil plunger to reset the bank and observe the action.
Maybe you can see what's going on that way. Don't use the reset bar to actuate it but push the coil plunger itself and watch the action. Also knock the targets down one at a time by hand and reset them a few times observing. They should fall all the way down. If not something could be binding the target. Could be a bit gunked up, and just need cleaning, or worn springs may need to be tightened up a bit so the target falls completely.

Just some thoughts. Hope you can figure it out and find an easy fix.