Pinout for Mot HF Antenna Tuner

[comtech]

Hello. Wondering if anyone here might have spec sheet/pinout of a Motorola F2260A antenna tuner used for HF. I have a very nice one, but no info on it.

On the bottom there is an SO-239 connector (input from radio I'm sure) and four bolts for electrical connection. I'm assuming one is power (+12V), another power (V-), the third I'm not sure about. Perhaps tune lock? The connections are labeled 1 through 4 on the outside, and lettered A, B and C on the inside circuit board (4th bolt is not connected).

Thought I'd ask before I start to experiment...

Thanks!