[ICOM] R70 issue

[Steve Sutfin]

Hello to the list,
  My Icom (aged) R70 receiver started having a problem after xxx  
years of good service. When I turn it on sometimes there is no  
signal, just the usual background noise. But after a bit it comes to  
life like normal but the signal dies after 30 sec. to 3 minutes. The  
voice doesn't get distorted when it quits but sounds more like wind  
blowing across the mic. If left on it comes back and sounds like  
normal for a bit then goes out. All voltages I've traced on the  
schematic are fine but my test gear is basic.
Any thoughts?
tnx & 73,
Steve k7dna