Jack wrote:
I have a 1967 172 with a MX 170B nav/com. I noticed not long ago that
the display was flickering from bright to dim. Now the radio will not
come on at all. Any suggestions.

First think to do is make sure your alternator is working (do you have
a voltmeter?). Flickering discharge displays are the first sign my
plane had that the voltage was getting low.