how can I tell if my 7jp4 is dead?

[Adam]

This was the other black and white set I got this weekend, after I saw it in the tv swap board on Sunday, I just had to drive 300 miles round trip to get a tv this old. This is the earliest tv I have ever worked on, the first one I have ever seen with electrostatic deflection, and without a flyback transformer (I am assuming no flyback, because I didn't see a hv rectifier tube) I will know more when I get my schematic this weekend (all my sams are far away in michigan).
The set just gives a white screen full of retrace lines, and a slight buzz on the speaker. I have run other sets with the tuner disconnected, and this set looks exactly like that, they would display retrace lines with the tuner disconnected, but with the tuner connected, no retrace lines. It is acting as if there is no signal at all, either audio or video. But I know the tuner is not simply disconnected, as adjusting the fine tuning will change the pitch of the buzz. Assuming this set was made back when there were seperate IF sections for picture and sound (again I don't have the schematic yet), and as I have neither, this would place my difficulties back in the tuner. But as it receives absloutely no channels at all, I wouldn't think the problem to be internal to the tuner. More like no power to the tuner, or no power heating the RF tube? Any thoughts?
Also, at some time this set was converted to have the tube heaters in parallel rather than series, using seperate transformers, and removing the ballast tube. It was done rather cleanly, and I don't plan to change it back, it actually seems like a good idea to me if you plan to use the set alot. But I wonder if this isn't the source of the current problem, like I said before, something like the RF tube not heating up.
As I am not that familiar with these really early sets, I am not going to take it apart until I get the schematic, and I will probably fix up that RCA remote set I was talking about elsewhere first, as I have already started fixing it, before I start work on this one. I will write more as I go.