Shifter Cone Screw Keeps Loosening, Thread Locker or Worn? Options

[Spoke]

Every 6 months I have to retighten the cone screw on the shifter. This time it came out real quick. I thought it might come out all together. I couldn't get 2nd without hitting reverse. The picture shows how much the screw backed out.

Not sure how much torque I applied but I was bending the allen wrench.

Questions:

Should I have thread locker on this?

What is the torque required for the cone screw?

Possible that the threads have been widened by repeated looseness?

Why didn't they put a bolt through this to really lock the hub onto the shaft?


TIA

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[GregAmy]

I know it's often said these are one-use items, but there's nothing with the threads that would support that contention, other than new ones come with a dab of loctite (or similar) on them.

In my case I clean the hell out of the threads (usually brake clean) and dab with blue loctite (I use the semi-solid "Quickstix" dispenser version) and - knock on wood - I've never had a problem in either car. And they're part of a standard underside inspection every oil change.

But that one with the buggered threads? Nope. And that may have buggered the aluminum casting in the process.