Comcast won't do anything for you unless they confirm you're having an issue especially with their equipment. I did at one Tim and it cost them $2k to dig a trench and run new cable from the pole. It's still expensive for them if they dont dig a trench.
90% is fine. Mine was down to 75% using their portable meter.
Make sure you're measuring the strength at the incoming line rather than after splitters/amps.
Now that I think about it, they'd rather give you an amp before replacing the line.
Good luck.
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