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no problem filing the 2nd ring, but the top ring is plasma moly (whatever that is) and way too hard to file

I made a simple fixture using a cutoff wheel as the grinder. Use the side of the wheel with the grind direction toward the inside so the flash does not create an issue and finish by stoning the edges. On those rings the ring is hard but the plasma surface is soft.

Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in Spring1989
95 Montero SR 3.8 DOHC Only one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Then a Gen2 SR with full coil independent suspension.