Welcome to Pinside, Ann!
The individual coils must be used to drop the targets? #11 is the reset bank coil, 12-15 are for drop targets 1-4 respectively.
My guess would be the driver transistor for coil 13 is bad. Check your schematic, it's probably one of the transistors on the solenoid driver module shown on page 26 in your manual.
Fun Fact: Suzanne Ciani (voice of Xenon ) is still working in the music industry today.
https://www.sevwave.com/bio