[MotorBikeLes]

I have never come across this myself, but I believe it is a well known problem with similar TEK HV transformers. Sometimes they are charred I believe. You could try drilling a series of stepped holes around the connection pin / pins thereby increasing the insulated path, and reducing likelihood of further leakage. Alternatively, unsolder the wires, cut off much of the paxolin, and add another layer above it fixed to the rest of the original with some epoxy resin.
Les.