Thunderbolt display goes black off and on

I'm working with a MacMini Late 2012 and a Thunderbolt Display (not sure which version). MacOS Mojave Version 10.14.

Lately, my display has started going black, and the only way I've found to get it going again is to disconnect the display from the MacMini, wait 10 seconds or so, and plug it back in. That has fixed it each time so far, but when I have to do it 3 or more times within an hour or so, it's very annoying. Some days, however, it doesn't do it at all.

My other problem just happened this morning, and that is the USB ports (where I have my mouse plugged in) stopped working this morning. I tried all three USB ports on the display, two difference mice, but nothing worked. Then I freed up a USB port on the MacMini and plugged a mouse in there and it worked, although it was not as responsive as when usually plugged in to the display ports. I found a post here recommending unplugging the power to the display, waiting three minutes, plugging in again, and to my relief the USB ports are working again. But how long before they act up again?

I only just discovered that the Thunderbolt display is no longer being made by Apple.....and their suggested replacement has very poor ratings here on Apple's site. Sure not looking forward to the possibility of replacing my beautiful Thunderbolt display.

Are my unit's issues something that can be fixed? Or do I just have to keep working around them until it dies all together...?

Thanks for any advice!

Ruth