OK, so i've finally dumped the coil having recalled i bought a spare and now this thing is rocking. It's still top heavy on my small batteries but the new coil seems to have sorted out the main problems. Cheers for the help. Dom
Good that it's working Dom but if you want to try and fix it to safe wasting a head. It might just have been that the head wasn't actually screwed onto the base properly and not pushing the connection pin out as it should as was suggested on here