Avcom PSA 65C spectrum analyzer problem

[jf4164]

I have an Avcom PSA 65C spectrum analuzer--a real workhorse.
Last night it quit on me..
I get all 8's on the LCD display.
No trace on the CRT but light green glow from trace area.
I can hear squelch thru speaker
along with a 60 cycle hum.
Same thing whether powered from 110 volts or 12 volts.

Any suggestions before I send it back to AVCOM??

Thanks

John Fulford
WA4VPY
South Florida