Need help with old hitachi oscilloscope

[digitalundernet]

Ive got an older hitachi oscilloscope v-1065a, I was using it to probe around on an audio filter I was working on when the traces vanished. The scope powers on, all the other info on the screen shows up I just cant see the traces. I can tell its still reading info from the probes because this model has a function where it can show frequency and it accurately shows the frequency of the reference signal on the scope. Ive tried every knob and function but I just cant find the traces. Has something like this happened to anyone else on an older CRT scope like this one? Its the only one Ive got, I need to fix this
 

[poot36]

If you are still getting display on the CRT the power supply is most likely ok.  I would suspect something to do with the circuit between when the signal is picked off to display the frequency and the actual sending of data to the CRT.  Here is a link to the service manual http://www.eserviceinfo.com/downloadsm/11465/Hitachi_V-1065A.html you will have to download the various parts and then open them up with a unzipper program.