Having managed to track down a 1920's Simpson Lawrence manual anchor windlass on eBay, I'm now in the process of trying to strip, clean, grease and rebuild. A simple design manufactured in cast iron, this should be relatively straightforward in theory. The main problem seems to be getting the gypsies off!
Classic Boat have published a useful exploded diagram of a slightly later model which has been very helpful. Having applied penetrating oil and steady pressure with a three legged puller, there has been no movement yet. Three weeks and counting...