It's just a connection board, all the logic is down below. I've never seen so much as a resistor on any of them. Look under the hatch on the tender shell and see what switches (or holes for switches) are there. The only S1 I find with PS/2 on the MTH site is the 2003 model which apparently wouldn't have 3/2 rail capability, so I'd only expect to find a smoke switch and a volume control. Not sure why they have ten pins, so maybe this was a prototype that never made it to market.
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