I don't think the gap is adjustable, except to make sure the iron core is centered up on its four mount screws with clearance all around for the magnet.
Mine doesn't hit but I found some filings in there that mean it does, maybe only at high rpm with the shaft's flexing/thrashing and causing the loss of the gap and a little scuffing.
All I could think of was to make sure its mounted centered on the 4 screws and checked for clearance. I suppose the outer faces of the magnet could be emory clothed for a little more.
I could take off the core, look for the scuffs and adjust it away from there I imagine.
I ride at middle rpms, the gearing won't let it scream, ever. No trouble with the coil or CDIs, maybe high rpm is breaking your wire.
This is an interesting problem.