I couldn't find any wiring errors and the voltages looked OK and I was running out of ideas when I had a thought about the tubes. Both tubes in the tuner are 9 pin and easy to mix up.
I had been using the tube placement chart in the Sams Photofact as my guide and it shows the 4BC8 RF AMP tube near the IF strip.
So I decided to take a look at the real tube chart in the Tandem cabinet. It shows the opposite
I'm just glad it's finally working and I didn't waste any more time on it!
The sound is excellent and the picture isn't too bad considering it's an original, nearly dead 21EAP4.
The brighter I make the image, the worse the focus gets. I believe that's typical of dying CRTs.
