Continued to work on the stove problem today. I removed the gas line assembly. You can see all the sensitive knobs and venturis wrapped up in a tablecloth. I brought this assembly to 3 machine shops, eventually finding out that a lathe will rotate the pipe while the thread tapper stays stationary. This would mean that the assembly with all the knobs and valves would be spinning around wildly, so it can't be done by machine. At the third place, Winks, I bought a 3/4 inch threader. It looks like a very large nut with female threads on the inside. It required a 1 and 1/2 inch or possibly a 1 and 3/4 inch wrench to spin it, which I did not have. In any case, using it to put threads on takes a huge amount of torque. I rigged up an assembly with a janky 3 axis Chinese table clamp that I had lying around. Being Chinese it is very easy to disassemble. I removed the topmost clamp unit and  to this I bolted an 80" long stud. Even with this huge quantity of torque it took a lot of back strength to tap the 3/4 thread. But it was finally done and I put it back in the stove. Viola, a few more inches of walking space!