I don't know what model KX155 you have Stan. There are a few different
one's out there. But on mine, the usual cause for the problem the OP
reported is dirty contacts. And the cleaning of them usually takes just a
few minutes. In addition, although I've not had to do it, the numbers can
be replaced separately from the control head. I called my avionics shop and
they said the same thing. Will fly there tomorrow morning to have them look at
it.
Would hate to have the comm or glideslope crap out on me on a long xc.
Hank N1441P