Well, the rocket is running again.

Darn, it's taken a long time to get it fixed though. But dint of some careful re-engineering and a replacement pump that was approximately similar to the original unit (hence the engineering: new mounting holes, re-alignment of the high pressure feed etc) we have ignition. Mind you, I thought it wasn't going to work at all - there's no air bleed on the new pump - semi self-priming - and it took several goes for the fuel to come through enough to catch.

Pretty sure that's it though. The hot water pipe seems to be getting warm much quicker than before. Here's hoping.