Are your customers having trouble, or are you opening the
coin door and dropping quarters through to test or rinse the bay when this happens? A Slugbuster II uses an infrared eye to see the
coin pass through. It validates the
coin electronically, but if sunlight shines on the eye it can't send a pulse credit.
If that's not the problem, swap the
coin acceptor with another bay to see if the problem moves. The timer could be bad and not the acceptor.