Chances are that it is a stripped or faulty gear in the cluster gear. Can't be too much of a big job to strip the speedo and have a peep at the innards , never done it myself though.
Hello folks, Have posted on here a couple of times but as I've just picked up my car I thought it was about time I posted in here and introduced myself. My wife and I are both keen drivers and after a series of modern cars just didn't click for us we have become hooked on the 60's & 70's. We started with a '69 Midget, chrome bumpers and wires which had a full running gear rebuild and then a '61 A40 Farina which has had an almost complete rebuild, a Mini Clubman estate with LOTS done to it and now the icing on the cake a '72 Rapier H120. You've no doubt all seen it's transformation by Michael so can't claim any glory for myself but it does give me the chance to spend the time simply enjoying driving and owning before I have to get into the other side of classic car ownership. There are a couple of little jobs need doing but they're tinkering jobs really and will be picking brains about them. Phil, it's nice to see a local on here, I'm over near the coast by Skeggy but I think you've got the better roads ;)