Netgear CM1100 - Errors on only 3 DownsChannel IDs -- 37 38 39

Hi, My new CM1100 modem on Xfinity Xtreme Pro (900 Mbps) shows errors ONLY on Channel IDs 37, 38 & 39. All other downstream Channel IDs show 0 errors. When the tech was last here a month or so ago.....there were 0 errors on all downstream channels. I know my general signal strength is a bit low -8 to -10 range. Just odd that its these 3 channels with errors. Any ideas ??