[Yaesu] Ft-107 problem

[Michael - VE3MKX]

Hi,   I have a FT-107 solid state HF rig with a strange problem.  The 
rig tx output is fine, but there is an intermittent problem on 
receive...  For example..... I turn on the speech processor everything 
is fine.  When I turn the processor off the receiver goes deaf.   Thats 
while in LSB, USB or CW.  When I change the band switch no effect.  When 
I turn the mode switch to CW-N or FSK or AM, the rig is fine. When the 
cover of the rig is off, and I touch the back of the 5 switch pc board 
(located on the top right) with a little pressure, the problem is 
rectified.  Even if I touch the board direct or touch it with an 
insulated tool the problem is gone.
 But here is the catch, I transmit CW, the rig goes deaf again!
I originally thought it would be a cold solder joint on the switch pc 
board or a cracked board.

Any thoughts ?

73 Mike