Maybe this has been mentioned.

The cable box at the TV location will reveal the signal strength in the setup menu. Why spend 1K to 4K on a meter when the box itself will tell you the signal strength?

Getting the detail will reveal if you have a problem per room, or at the demarc. Move the box (boxes) around to find the problem. Get the cable company involved to solve it. They will tell you if you need to run new wires after the demarc.

Hope this is helpful.