[Chuck Schwark]

Might I suggest checking for marginal tubes, and/or an open or shorted IF transformer winding.

Also, if you flushed a mica trimmer with a contact cleaner, like DeOxit, there could be an oily residue that's throwing the capacitance of the trimmer out of spec. Many contact cleaner formulas leave a non-oxidizing film behind when they evaporate. I use DeOxIt at work for contacts only because of this.

Try flushing the mica with denatured alcohol to clear off any oily residue, that's good for metalic contacts in a switch, but bad for a mica trimmer cap.

Been there.

Chuck