Hi Mike
Nice to hear from you. Yes both donor bikes performed ok prior to and after their BMS units were removed (to try on my bike) and subsequently refitted.
On my bike the above fault persisted despite having fitted a BMS unit from each of these other bikes. That led us to believe that my BMS unit was ok and the cause of the fault was elsewhere and so we split the wiring loom open to enable us to physically trace and inspect the wiring. The earth on the coils is common and as the other 3 work ok this rules out a bad earth.
After confirming that there were no wiring faults, we decided to try putting my BMS unit onto one of the donor bikes and were surprised to find that the fault transferred across to the other bike (the fault thankfully cleared after it's original BMS was replaced). This clearly raised suspicion again over my BMS unit except fitment of a BMS unit from 2 donor bikes did not rectify the fault (no spark).
The other unit (ZFE) was not switched and I am wondering whether this unit may be faulty?