Just a follow up for those who care,

After adjusting the grid bias down enough for the dots to go away all
day, I found the signal to be too weak. I dug into it to fix it
properly, and traced it down to an IC, forgot which number it is, but
it's a Tl072ACP, an 8 pin dip on the hv board. Thanks for the help,
got us back up and running again!

Thanks,
Steve Kamego