I'd spent several hours getting a Square Head up and running. (Finally found a jammed latch plate on the OB "O" sequence relay) Worked great for 15-20 games...then: when the ball is drained the ball count stepper (works smoothly manually) does not decrement a ball and the 20 unit bank doesn't reset, but activating the ball drain switch trips the delay relay and nothing resets; all the previously scored Xs and Os remain lit. When I manually retrieve the ball the game works fine, but still on ball 5. Everything resets as it should when I start a new game. Puzzling since I had played a number of games without adjusting anything and the problem arose.
I'm kind of new to this, so keep the answers simple, please! Ordered the schematic today.