Only thing I can think of then is to try to find a wiring diagram and bypass any wiring that operates any cut off switches. I suppose it could be two dead coil packs in a row...maybe
I've had some replies directly from Makita...quite impressed! After a few emails their engineer called me. He said it's probably the flywheel and he changes both the coil and flywheel as a matter of course. You wouldn't think flywheels could go faulty!
They offered for me to send the machine back to them for repair free of charge except for parts and postage but I don't think it's worth my while. May see if I can get a refund on the coil and buy a flywheel otherwise its spares/repairs on the bay.