[Ron Ramirez]

Hi Gary

Assuming you're working on an early 70 (without AVC), here's what I would check:

• Antenna coil (2) and RF coil (6);
  ALL wiring from tuning condenser to the various points under the chassis;
  tightness of the screws on the sides of the tuning condenser;
  the RF amp tube, Type 24.[/list:u]
  I think it's probably a combination of bad antenna coil (2) and/or RF coil (6) and wiring/screw tightness issue on the tuning condenser.
  
  The second Type 24 tube from the front is the mixer tube, so your problem has to be ahead of that. The wiring/screw tightness on the tuning condenser can cause lots of intermittents.
  
  Hope this helps. Happy troubleshooting!
  
  (edit) Well, Chuck and I answered at almost the same time, so now you have two votes pointing to those coils. Take a look at them right away. Good luck.