Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I have a Weeden 665 whose throttle screw is stuck and looks 'lime' frozen.

Now, while the engine runs well, I would like a bit more control.

The fitting it screws into is lead, so heat is mostly out of the equation, and
forcing is a bit too risky for me. 

If any do-it-yourselfers have an answer, I'd appreciate your sharing it.  I think
this is a pretty common problem.

Thanks,
Wayne