Update. Tried a number of motor factors here in Cyprus & was unable to get the A plug. I soldered a wire to the plug lead metal braid & the other end to a washer & bolted that to the engine. I also left the original cable ties securing the plug lead to one of the engine standoffs. The interference problem has disappeared.
Thanks to everyone for their input.
I have a giant scale CMPro Zero kit & a DL50 engine that I was going to sell because of the problems I was having. Now, I think it will be my next project.

Regards
Jim