You can also remove the connector to the RC valve servo and run it with 12 volt.
Connect 12V to W and W/R for a second and see if the valves move. Swop the 12V wires (to reverse polarity) and see if they move in the other direction.
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Poul
"If Life Gets Boring, Risk It!"
MC21SE, KISS box
MC21SP, HRC box, racing loom