Problem recording the Mic

[Ton]

Hi all,

I have a problem recording with the microphone on my psr-S975. The mic I have is a
"professional vocal mic/ C -1537 imp. 500 ohm. ".   It used to work real fine on my tyros 4. It also works fine in talk mode on the psr. It is installed according to the instructions in the owners manual. It has been suggested that it could be the guitar/mic switch at the rear.  How can I work out that is the case .
I am a loss as to what else to try and open to all your suggestions. Thanks for your help.

Ton .