Hi Chris,
I just went through this (breaking squelch) problem with my Borgelt B-100 and I
found some very interesting things:

1. When the NMEA cable from the cambridge GPS was moved near the radio antenna
cable, I got full squelch. Move it away and the squelch went silent.

2. When the cable going to the LCD display was moved near the antenna cable, I
got full squelch. Move it away and the squelch went silent.

My fix was to move the antenna cable (RG-58) to the other side of the
instrument panel and routed it out the right side, about 12 inches AWAY from
all the other cables.
JJ Sinclair