high error rate

100000+ errors on only 1 channel (#8) - low SNR 29.1 in the 26 hours since modem reboot. other channels SNR 35-43.

No change in cabling (RG11),  no change in modem or nearby equipment. Had 0 errors on all 16 channels for quite awhile.

Speed still fine.  tracert to www.comcast.net went 10 hops. I don't see what I can do different. 

If it never gets worse on other channels, I'll be OK. 

Just curious how only 1 channel goes hinky.  [ motorola MG7550 bought 4 years ago ]