[Bruce B]

I am on my 4th old radio repair and now I have this radio working but it has an extremely sharp, like a crack, thin, tunning width. There is no width at all, it's like tunning a crystal detector, it's either on or off signal. The sound of the audio is somewhat distorted while the radio is warmed up. If I turn it off and let it cool, the audio is excellent when turned back on. It starts to deteriorte after about 3 minutes. 
  This radio has been completely re-capt. There are no original wax capacitors in it. All the capacitors are blue, Aerovox, capacitors. I have tested most of them under voltage for leakage and they all seem quite good and spot-on. I have replaced the capacitors adjacent to the audio tube anyway, because of the distortion thing, but no improvement was made. It's not fun to replace absolutely good parts, but I did it anyway. I can put an audio signal into the 2nd detector and the radio sounds as nice as an old radio can sound.
  The resistors are a different story they all seem to be original, dog bones and most are reading from a little bit high to somewhat high and I plan to start changing them out. I don't feel though that the resistors are causing this sharp band width problem, so I am trying to figure that out separately. I forgot to mention that as the radio warms up it will drift from its sharp tunning point and as the distortion begins. When I bring it back into tune again, the signal is still quite strong but with more distortion. I have aligned the IF and RF. The IF went well and came up and peaked quit easily but the the RF tuning was sluggish and had little responses to padding adjustments. I don't know if I have 1 or 2 issues here.  
  So after all of this being explained, I am in hopes that someone can guide me to the next thing I should be looking into?
Bruce B