Hi Graham,
Not shorted out, but nearly blew a fuse :-D
I seem to think the winch rope on your K6 is not to full length, in fact it could well be one that I managed to save from an army earthmoving tractor. I found one that was damaged near the drum end and was replaced, it then went on either your K6 or the green one. The correct length rope will come up to the top of the drum. Try pulling it out to check length, if you have not done this before, there is a dog clutch lever on the winch, for free spooling and the band brake. You might need to pull it out with another vehicle for first few times until brake surface is clear of rust.
I took the green K6 from the museum to Parham steam rally many years back and the site was muddy when we went to go, the K6 walked through it, providing you take it easy, don't forget there is a low range in the Aux. box.
Richard