Hi Gonna put my 2 cents in here..You don't mention how low the power output is some of the other guys hints are all possible causes,,here's my thought...have u ever done an rf alignment on it?? Iahd an 830 yrs ago..And I used to re align it abt every 2 yrs (rf allign & If align) very easy to do if u have the orig manual, they used to pack the 2 align sticks wen you bought them new..if u don't have any non metallic align sticks look online and get a set,,any way good luck with your problem hope it's an easy fix for you..Again the procedure is outlined in the back of the manual
73 Larry K3BFQ