I have a hydraulic Maxwell
that gets the same condition occasionally. It drives up and down. There is a pawl that will will stop the chainwheel from turning in the down direction. It is there to be used to raise the anchor
manually in the event of an hydraulic failure. I have used it to force the clutch
to disengage by driving it hydraulically against the pawl in the down direction while the clutch
manual calls for dis-assembly of the upper part of the windlass
periodically to clean the junk out of these moving parts
, and lubricating them. This will reduce the occurrence of the clutch locking up.