The first thing to do is to carefully observe which of the possible relays with a switch that activates the score motor is energized while this is happening.
There are 10 possible relays, plus the switch at motor 1C.
The switch at motor 1C closes to help keep the motor running to reach the next 1/3 rev, so if that switch doesn't open properly, then the motor will keep running. One possible cause is if the switch dog is caught in a 'lifted' position, keeping that switch stack hung up.
Otherwise, need to determine which of those ten relays is still stuck on. Then can debug the path to that relay to see why it's still on.