Apex 460 trouble

[Greenie]

Hi. I did a mot to my Apex 460 10 years ago, and it's been working great ever since. I have never used the polar pattern switch on the PSU, but finally go down to testing it today. The mic then stopped working, except on th figure of 8 position. What could have happened I wonder?

 

[Khron]

Broken connection between the switch and the pattern wire? Or between the B+ and the "top" of the resistor divider string? Or just a dirty / busted switch...