Bad wishbone? It's a "yoke" that slides a gear into the fine tuning slug in the tuner. Zenith was famous for bad wishbones. I may have one. The gear teeth get eaten, but some might still mesh.
34-?? WAS the part number, but Zenith went and made it 834- or 800 - something, like the kits. We ordered them in 10's from Bluefield Distributing in the 80s. Our tube caddy had a couple for house calls.
Zeno? - Any recall of the part number???
He's know for sure.