Dan was talking about this tonight. Electric shocks from the frame are not good.
I personally know your bike and the wiring loom. Dan parked (abandoned😱it in my garage for several months. The bag of spare coils that you received had the good and bad mixed in. Or that at least the way I gave them back to Dan.
Since then Dan persuaded me to get back on a bike do i have bought a zzr600 it runs well but one coil sparks from the attachment points to the frame.
One thing to check on the 400 is the main earthing point on the engine. ( above gearbox under carbs) it was clean and tight the last time I saw it, that was some time ago. If it's loose it could explain the shocks.
