[gregb]

I just wanted to pass along a little something I discovered while working on a couple model 80's. After cleaning up and recapping/recarbing I was able to get them working ok but not great. They were not very stable and just about every time I turned one on I would have to readjust the feedback or the oscillator would quit working. So on one of them I implemented all of the posted upgrades, tried baking the oscillator coil and there was some improvement for sure but still not what I would expect. I struggled for some time with them without much success. 
What I ended up finding was on the sides of the tuning capacitor there are a couple screws that hold things together and the wires attach at this point as well. They were not very tight and there was a slight amount of oxidation on the small plates the wires solder onto. I cleaned up the plates and tightened the screws and now both sets work perfectly. The one set has all of its original value resistors and capacitors ie none of the posted upgrades and it works perfectly with no issues at all. Oscillator is rock solid and I was able to get a very good alignment that seems to be holding steady, my dial scale is reasonable accurate. I am really surprised at how good these little four tube sets work, all of my local stations come in loud and clear with just a short piece of antenna connected. 
So if you are having trouble with your model 80 this might be something to have a look at. Good luck and happy collecting!

Gregb