Intermittent Windlass Problem

[Steven UK]

Ok so i stripped the windlass motor down again, brushes are free and about 1” long I checked the resistance of the winding negative to each positive is 20 and 40 ohm. Between each positive it is 0.3 ohm. Contractors are working as expected ie energising the wires individually. The gaps or insulators between the commutator are all clean. I’m going to file the brush faces because it’s the only thing I can think to do right now.

[Dsanduril]

Those resistance values are suspect. Even if you have 0.3 on the winding you would get I=E/R -> l = 12/0.3 = 40A, which is low for a windlass draw (~500W). At 20-40 Ohms you're looking at less than 1A.