Tech question - picture distortion

[mashaffer]

I have a freebie RC color TV model GGR649L Manuf. Oct 1982. We use it only for movie playback and don't even have an antenna for it. We feed DVD player into a modulator and then rf cable to the TV for video.

We often have distortion of text such as credits and subtitles (but not always) that make it unreadable. Often when the text starts to fade out it clears up for a second as it is going away.

I thought it might be too strong a signal so I tried an RF attenuator on the signal line with no change (I am not too savvy when it comes to TV). Any idea as to whether this is an adjustment or just a dying set (or other)?

Appreciate the help.

mike