Here's what I have:  G90 about 6 months old.  When its turned on, all I get is a HORRIBLE hiss and static coming from my amp.  I have green lights on the unit.  I have tried high and low settings, changing batteries, changing cable (from transmitter to guitar).  The hiss is severe, and the level of audio is almost nothing.  How do I go about getting this fixed.  This is not interference, as my bassist is using a g90 and my other guitarist is using a g50 in the same space.  I have had a few issues with this unit (cable was no good, transmitter didn't work [replaced by GC as this was a few days after I bought it]). I am frustrated and just need a working unit.  Any help appreciated.