Sounds to me like the connection from the switch->cpu is fine, but from CPU or Power -> solenoid is borked somewhere. Depending on what's actually causes it to fire on that machine...pretty sure both my machines are "dumb"...they just fire whenever the switch closes and there's no CPU interaction needed. Don't know about the DMD gen stuff too much, but if they work that same way, might be a bad connection between the switch and the solenoid.