Help with Intermittent Harken Power Winch

[Whomda]

We went out sailing for the first time in several weeks on our cat, which has 3 Harken powered winches Harken 46.2 ST.

One of the winches worked perfectly, the other 2 winches stopped working: if you pressed the winch button (either one), they would spin for about 1/2 a second, then stop spinning. This was with no load. Engines running, so the voltage was good (and the one good winch continued to work as expected).

After about 30 minutes of sailing, both winches began working perfectly with no evidence of trouble. They never failed again, despite any combination of engines on or off, with full line load.

Weather was cold but not extreme (southern California winter, maybe high 40s).

Voltage seemed fine, engines were on with alternators running, the measurement was good. as well as the fact that the third winch worked just fine.

All winches lubricated maybe 8 months ago, all spin freely and hold high loads fine. Manual winching using handle worked fine. Confirmed the center pin was not pushed down preventing power winching.

Any suggestions where I should check to see what might have caused this unusual intermittent power fault?