As it turns out, it appears my winch may be fixable. A neighbour opened it up for me and insides appear ok, but the bushes are jammed. My younger and far stronger helper can move the lever with difficulty, but it is beyond me. I'm going to drain the diesel in my fuel tank and use that to let it soak for a few weeks.
I have one the same, a Simpson and Laurance, and after 6 months of the gipsy and clutch it being seized, I finally managed to free it and gave it a good oil and wet and dry paper to polish the clutch. I have an electric one but like the manual so will see how she goes now its back in working order. I have been manual hauling the chain in shallower water and my anchor rope in deeper. Once or twice I used the sheet winch when there was a bit of current and a difficult retrieval. I have 50 meters of chain so I'm glad to have the old windlass back in operation.