FM Tuner Drift

[Winky Dink]

I put together this radio with the best parts of an H725 and a J725. The H725 was the model my Dad had in his bedroom for 50 years, and I needed an FM radio to listen to while I worked. Esthetically (my personal taste) it's a radio that only a mother could love.



It works well and sounds good, but the FM tuning has to be very precise and often I can't listen for more than a few minutes before it drifts into distortion. This is my first foray into FM, and all I did on this set was replace (as needed) caps, resistors, tubes, and selenium rectifier.

What should I look for to regain stable FM tuning?