Help! frustrated with 58 Space Command

[Tubejunke]

I have a 1958 Zenith Model C4007R Space Command with the 18C24Q chassis. The set has virtually no vertical sweep and only a hum for sound with no signal. I figured electrolytic trouble for sure. Well, I disconnected the leads to the cans and did an ohm meter "kick" test and found nothing unusual. No low resistance readings like I expected. I replaced several, but not all of the electrolytic caps and the set has not improved at all. I have replaced around 6 of the white tubular paper caps. I keep thinking I should easily run across some component with a way off reading like a shorted cap or something open but I just havent hit it yet. There are 2 black beauties in the vertical section that I havent touched. I dont think the small value caps would cause the serious ills of this set but I may be wrong. One thing I want to note is that there is a 5U4GB in place of a 5AU4. The set is producing DC, but could that tube cause some kind of short? A site that has sub info did not list the 5AU4 as a sub for the 5U4. They both have the same pin out so there should not be a short. I guess I'm hoping that some good folks out there are familliar with this chassis and its charicteristics. I know Zenith used this and variations of this for a few years. I notice that some scematics call for 5AU4 and others 5U4. There has to be some difference. I should be getting at least some life out of this set by now. It is more than half re capped. It will be a good one once I get it staightened out since it looked like the back cover had never been removed and all stock tubes. I figure low mileage. I also need a remote....
Thanks on advance!!