when the misfire starts it will even do it when revving stationary, the water test was simply pouring a couple of pints of cold water over it as it was running and revving, to which it did appear to help for a brief period.

The amplifier is mounted on the n/s inner wing in its own clear space

I can't find the spare I had to test as that was my first thought, I will replace it as a matter of course, even if to just eliminate it,

Cheers tabetha

Stu