[Drake] R-4B mechanical question

[Jack Antonio]

I'm bringing an R-4B back to life, and have a question
about the selectivity switch and its shaft coupling.

The coupling from the shaft to the switch is a brass sleeve,
but what is inside the sleeve to provide the tension? Mine
is missing whatever insert there is, and am wondering if
there is a replacement or workaround. So far I've tried brass
shim stock, copper flashing, and a small bit of #20 solid wire,
but nothing has been solid enough.

Thanks

Jack Antonio WA7DIA/4