It appears to be an old rotor arm as the current one is complete and in good working order. I have removed the distributor and dismantled it but it appears to have strecthed one of the springs in the bottom. Ah, I may take your advice then as there is very little play in the main shaft...

Thanks for all the help guys. I've pulled the distributor apart and found what appears to be part of a broken rotor arm stuck in the mechanical advance holding it shut. So the problem was within the vacuum advance or mechanical advance. Time for a new distributor I think.

Hi guys, 1968 series 2a with a 2.25L petrol engine. It starts and idles absolutely fine, and when warming up (~first 5 minutes running) it pulls really well and accelerates. After that when under load, going up hill or pulling away from lights, it fraps and bangs and misfires, making it...