High tapping may be compensating for a poor connection in the 100 point scoring circuit or mechanical binding or friction. It might fix the problem but might also be driving the game harder than it needs to be.

The run scoring circuitry is fairly elaborate with a lot of moving parts. This explanation is based on the Play Ball schematic which may differ slightly from yours.

There are three interlock relays (A, B & C) that keep track of where the base runners are. There are also four relays for the four different hits (E/Single, D/Double, T/Triple, H/Home Run). When you get a hit the corresponding relay for that hit, and all of the lower hits all fire together. So a Double for example will fire both the D/Double and E/Single relays.

A hit will also start the Score Motor which in turn sends 5 pulses to the Hit Unit stepper. There are notches or gaps around the edge of the Hit Unit wiper disk that tell the game when to stop advancing the Hit Unit stepper. It should always stop when the switch following the edge of the wiper disk falls into one of those gaps.

The first four positions of the Hit Unit stepper correspond to the four bases. To figure out the number of runs to be awarded for a hit the bases have to be evaluated one at a time and in reverse order to get the right answer. So the first position (before the first step is taken) evaluates any runs scored from third base. If there's a man on third base (C relay) and the hit is a Single or anything higher, one run scores. Then the Hit Unit takes a step and looks at 2nd base. There if there's a man on second (B relay) and the hit is a double or anything higher another run scores. The next two steps check 1st base, and then Home Run. Any time a run scores the Hit Unit completes the circuit to the F/Run relay which fires the Runs score reels.

The Man on 1st (A), 2nd (B) and 3rd (C) interlock relays have to go through a similar computation to figure out whether or not there is a base runner on base after a hit. To further complicate things the A, B and C relays are hard to get adjusted properly once out of alignment and are subject to becoming magnetized and misbehaving even if the circuit is working properly.

I would start by doing a lot of experimentation and figuring out what works reliably. For example:
- Do all hits start the Score Motor?
- Does the Hit Unit always take 5 steps?
- Do the Single, Double, Triple and Home Run relays behave as described?
- Does a Home Run score reliably?
- Does a man on 3rd and a single score reliably?
- Does a man on 3rd and a double score reliably?
- Does a man on 3rd and a triple score reliably?
- Repeat for 2nd base and 1st base.

Sorting through this will take some time so be prepared to walk away and take multiple runs at it.

/Mark

I'd recommend starting with experiments that use just a single base runner to reduce the number of variables. If you only get 2 runs for a grand slam for example you don't really know which two runners worked and which two didn't.

Something else you can try to better understand things is to disconnect the Score Motor at the service jack and then manually turn it after getting a 'hit' so you can watch the relays and steppers at a slower speed. Just be sure to always turn it 1/3 of a turn and return it to an index position. If you leave the Score Motor between index positions you'll never be able to sort out what did or didn't happen.

I'm glad you got it sorted out. The run scoring calculations are pretty elaborate and interesting. I find that the game can often do the math faster than I can.

I'd like to get to GSPF. I'm curious, do you think there would be any interest in an EM repair class at or near the show?