Asteroids Image Dim & Stray Vectors

My Atari Asteroids system starts up flawlessly and runs fine for 10-15 minutes before the screen dims and you can make out the vector traces:

Searched and scanned the Technical – Videogames – General Repair And Help forum on the IAM/KLOV website, and while a few of the threads seem to indicate a similar issue, non of them match my symptoms exactly. Guess I’ll have to post my issue and see what they recommend. My first guess is that a cap on the monitor is going bad an when it warms up and fully charges, results in the screen issue.