I have a MIJ L cymbal arm that came with the red sparkle set I just bought last week, but the wing screw was stripped off years ago and the arm is frozen in place and won't raise or lower to the height I need, so this morning, I Googled machine shops in my area and came up with one in Wharton, NJ.
I used to use an old gentleman right in my town who had a machine shop in his basement, but he passed away last year.
I called this shop in Wharton, spoke to the owner, an eastern European gentleman named Ziggy, who asked me to take a photo of the L arm and send it to him, which I did. He called me back and said he could fix it. I stopped over in the late afternoon and dropped off the arm and a new wing screw. I asked him what the cost for repair would be, and he said, "If I have to buy a tap, about $10, but otherwise, no charge. Just buy me a six pack of beer. I'm always happy to help a musician."
If he can fix it, I'll buy him a case of whatever beer he wants. It pays to make friends with a machinist.