Sound problem with 737NG

Good day all. I've been having a problem with the sounds in the 737. When I turn on the APU genrators there is a clicking sound. Before I re-installed the plane again it would just click once then stop (which I assume was normal). But now it keeps clicking throughout the flight. The only to make it stop is to turn off the generators, but then A/T won't arm and hold. Also, it's not the sound you get when adjusting the pitch/trim. Any help to make it stop?P.S. I looked and it's not in the sounds file under the 737-700.-- Jake