Thought I had everything sorted out with this one. Played several test games and everything worked fine. A few days later and the trap door does not kick up high enough to let balls eject. All other coils and switches appear to be working. So far I've checked fuses, cleaned the trapdoor post shaft & coil sleeve and reflowed solder to the coil lugs. Same result- it's just giving a weak pulse, not strong enough to kick up all the way.
Is it possible that the coil just needs to be replaced? What are the next steps for troubleshooting? Thanks for any ideas.