Since this particular modem was installed on 5/18, its transmit power has been 49-54 on scheduled polls. We want it more like 41-48 ideal, 52 max. You're also reading a high power adjustment count and a high T3 timeout count. This all adds up to something going on with the signal back from your equipment to us. Your digital receivers also report high TX levels, though they tolerate them better, but that points to a problem with more than just the one outlet.
Could be anything from a bad splitter or amplifier inside or on the side of the home, all the way back to the tap at the pole or pedestal. Average street-level readings are good. So at this point I'd recommend a service call.