The AGCO parts book shows the Switch in one of the 5040 Electrical Circuits. Item 16
The one on my 5040 stopped working too.
IIRC, the assembly is swaged together; the metal body being swaged or crimped to the phenolic (?) tower.
To get it apart I had to carefully turn the swaged portion in a lathe until the phenolic came out.
I think the contacts were just dirty and corroded. To re-assemble it, I tapped the base for some small screws and drilled the phenolic part for them.