Chum,
Your TVFOOL report doesn't suggest any reason you shouldn't be able to receive a dependible WPSU 3.1 (15) especially at 25 feet of antenna elevation, unless there was a change at the transmitter/antenna.
Since this is a seasonal change noticed when the leaves left the trees in your area, my first thought is you may now be collecting more signal or noise than before, possibly including increased multipath signals that the trees had been attenuating for you. If so, the signal and or noise levels may now be too strong for your receiver to decypher and reassemble into a picture and audio.
Also, all pre-amplifiers and distribution amplifiers add their own noise to an RF signal, so an increased noise level by nature, plus amplifier noise may be the problem.
Have you tried to receive your stations, bypassing the CM amplifier? The reason I ask is because what you said: all other stations come in at 100 on your 'meter'...
Although it may seem counterintuitive, in the digital OTA world a clean, low-strength signal often trumps a strong signal. Example: I split a 1-edge signal 4-ways around my house from a 300 watt analog translator located about 40 miles from me using NO amplifiers at all.
I hope this helps and please keep us posted.
Jim