I have done all these things, reflowed the solder on the optos, reflowed the solder on the board, used hot glue to hold the connectors, etc. Here's what I found, the left opto at the ship is in a very tight location and the wires were routed over the post next to that opto at the factory. When they installed the plastic on that post and tightened it down with the nut on top of the plastic, they pinched the wire. The game worked fine the first few years, but with all the vibration a pinball machine has it eventually broke through the wires, so I installed a new opto on that side. The game was still acting up, but not as often. I decided to just replace the opto board and now the problem is gone. The board is only $15 and they are prone to failure, so I really wouldn't waste my time playing around with it...check the opto harness on the left side in front of the ship and replace that board.

The board at pinballlife:
https://www.pinballlife.com/index.php?p=product&id=2219

Good luck!