sound buzz

[radio nut]

Once again my Muntz is giving me fits. I thought I was totally done with this set but it has other ideas.......
Turn it on and the sound is great......give it about an hour and it slowly starts buzzing through the speaker.......
text on the screen is worse.
The discriminator coil is a replacement from moyer's. All out of tolerance resistors have been replaced, and ALL of the caps in the sound circuit are new.
Although ceramic have been put in for bad micas.
Once warmed up well the buzz starts as soon as the dvd player I use gets turned on..
Any ideas?
Also This set does not have any power cord to ground interference caps.