Legacy HD DVR cable box intermittently working

We have 2 Motorola DCX3400 DVR boxes. We've had some issues the last couple of days after 10+ years of no issues. We've had the picture freeze, the screen go blank, Following the advice of the first chat online, I unplugged both the TV and DVR, waited, and plugged back in. It would work for awhile, then do the same again. All this was after swapping out HDMI cables. The next day it was doing something similar, and during that chat, I was told to re-pair the remote. So I did that, and again, things seemed to be fine. Today, that issue repeated itself, and then the screen would go blank (DVR on, TV on).

All the while, the cable box would still actually work again. When the screen would go blank, it would allow me to change the channel, and then things would be fine...for a bit. It's been going blank about every 30 minutes, but the channel change is taking care of that issue, but it is annoying to keep doing that.

After being told that unplugging would fix the issue, and that re-pairing the remote would fix the issue. I'm hoping that a Comcast Tech Support might be able to help with some different troubleshooting on this issue. With the box mostly working, I'm not sure if it's the box itself, or if there is some other issue. We have an identical TV and DVR (Motorola DCX3400) that is not having the issue, so any help would be appreciated.