Problem---supercharger third magnet not energizing. This caused the supercharger to run slow, and sometimes caused the ball to fail to make the second loop, loosing points and sometimes draining right down the guts.

Diagnosis---Supercharger magents and beacon light all run off the General Purpose Solinoids at J122. Pins 1,2 & 4 run the magnet coils. Tested all for the Transistors relating to these soliniods (Q20,22,24,26) as well as the pre-drivers, diodes and resistors relating to them. All tested OK. Swapped another driver board to confirm that the board was not the problem. Magnet still not working, so not the dirver board. Checked that all magnets had voltage at the coil. Checked continuity from wires at J122 to the accelerator board under the playfield. Plug at J122 was a bit ragged so replaced it, but the main problem was not fixed. Checked continuity from accelerator board out to the coils. Was a bit intermittent in places due to worn connectors, replaced them but problem persisted. Coil swapped to another location worked OK, so def not the coil.

Problem now narrowed down to the accelerator board. All opto switches operating OK in test mode, accelerator board LEDs show 12v OK and optos activating when they should. All opto switches cleaned and solder reflowed for surity.
Checked all transistors, diodes and resistors and found them to be in order. Reflowed solder on the header pins and checked continuity from pins to next component, no problems found. By now, pretty much the only thing I could not test were the IC's on the accelerator board.

Repair---Larger components I will repair, but ICs are a no go zone with my soldering skills. Sent the accelerator board off to Ken (Skybeaux) and it came back looking like it had never been repaired. Ken confirmed that on removal the 4071 chip tested bad, but he could not test the LM339's. All 4 IC's replaced with sockets for saftey and future ease of repair. He replaced a few diodes and transistors for safety, as some tested slightly out of range.

Problem fixed, supercharger now working as good as it ever did.

Thanks to Ken for the repair job, hopefully this log will be of some assistance to someone in the future.
Dave