[Blue Suede Ted]

Hi, I have I have problem with this set: When hot, after several hours of use , the tuner or I.f stages go slightly low gain. It’s just enough for the stereo decoder to drop out. The decoder stays operational when tuned to a strong local station. I think it’s probably due to a temperature conscious component rather than a dry joint as it is not sensitive to vibration.
Any ideas on what could be the cause of this problem would be much appreciated.
Regards
Peter