Hi Guys, thanks for all the advice. I tried starting as per the RAF FRCs yesterday (left mag only) and it appeared to start better. Only trouble is, problems do come in twos or threes! When I press the starter button for the first time, the engine will not crank, but there is a whirring noise from the bulkhead. Second push activates the starter, but the engine cranks very slowly. Battery voltage is fine
Luckily the engine normally fires after a couple of turns of the prop.
So my diagnosis:
1. Starter relay knackered.
2. Starter knackered.
ps recently replaced the bendix.