I'll take a stab, first try attenuation if that doesn't work then try these in the order listed, turn off Digital and Analog ADC, ADC 0 DAC 0, then open p25 threshold to 50-95, still no improvement try 72 or 56 with DSP. If you are listening to multiple sites under one programmed trunked system tighter p25 thresholds 75-95 are to keep sites rotating, if you loosen them up to 15-95 you'll need to have the sites programmed as different systems altogether.
On my post it's suppose to say "Digital and Analog AGC" not "ADC". As suggested your locals might know better, but if they aren't forthcoming with info, that won't be much help.