This is a rotary trumpet that recently came through the shop.  The 1st valve lever key was broken off (left).  The clockwork spring had also broken (center).  The axle had rusted and stuck to the spring drum inside the housing.  The third photo shows the original spring drum with the rusted axle still inside (it could not be removed so I had to cut it off in order to disassemble the key housing) next to the new one that I had to machine to replace it.

The new axle was made from .101" oil hardening drill rod with a brass knob press fit onto one end (left) and threaded to 3-48 on the other end with a brass nut to match the knob (center).  The levers are installed by riveting.  There is a round end that is inserted through a hole in the housing and headed over.  The old one was drilled out and the new one was inserted and installed just like the original (right).  The paddle was made from 16 gauge Nickel Silver sheet brazed onto a shaped brass rod.

On the left are all the parts that I made for the instrument and on the right are the keys reinstalled on the Trumpet.