Sounds like its your mechanic's problem, not (really) yours. I'm surprised he didn't know better. I always cut the steel nuts off (across the threads). I still buggered the last one I did a little, but the threads that are left (about 90%) are enough to keep it together.

I think repair of these has been discussed before on the forum- do a search. I should think a more available 300D turbo unit from a boneyard would work but may require a little mounting ingenuity.

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