Robbins and Vass are a good distance apart. Do you have both sites in Moore County programmed? What programming software are you using? The Carthage site is much closer to Robbins.
Mine started doing that also, and the T stopped flashing at the top. I did a total reset on the scanner and wrote my scan list back on it again. It started picking up all the local P25 traffic but, rarely picks up the other counties that it picked up nice and strong before. I've heard the ws1065s were prone to this problem because of the eeprom memory starting to fail. I went ahead and ordered a couple eeprom chips and replaced it but, it's still the same. I guess for $1.36 each, it was worth the try but I sure don't miss working with those tiny smd devices!
I remember years ago I owned a RadioShack PRO-164 that stopped trunking like that as well. I ended up selling it as is. Yet its twin, my PSR-300 has been working flawlessly for the past 10 years. Guess it's all luck of the drawer