[ICOM] 781 problem Mic gain gos away

[KG4LRU at aol.com]

Has anyone run across on the 781 Mic gain just go's away, if you turn  it up 
its starts driving again after few minutes it returns to normal, and you  have 
too turn the gain down again.
It comes and go's I have checked unit with other mic and this one has been  
in for a complete  service .In the last two years. I have run across one  other 
friend that his 781 exhibits the same symptoms. Also Turning the radio OFF  
and back on seems to cure the problem for awhile. Any Ideas Icom service 
doesn't  have a clue?
 
73
Phil AI4DQ