I've repaired three by welding on the xtrememotorworks "square". In each case I've removed the trunion arm, but only because I had to go into the hydro for other reasons. I would not hesitate to weld it while still in the tractor, with a wet rag on the arm. Here's a few pics of the sequence of the repair. If you take it out, you can weld both sides, but it's not necessary. Be sure to replace the springs--that's important to assure proper speed control. The blue paper towel in these pics is only for picture clarity.
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