[Kenwood] problems with the 599d twins

Sat Jul 20 16:22:06 EDT 2013

Have a pair of twins,t599d/r-599d. When following the manual to tune the transmitter ,every thing goes fine , easy 100 watt output . The manual says to tune the transmitter with the transceive/ seperate switch on the back in separate,the light is then on for the transmitter vfo. when Iam done, I push the switch back to transceive, transmitter light goes out . I then put the receiver - transceiver switch to RX and the receiver comes to life. 
When I key the transmitter, receiver mutes as it should..........BUT NO output from the transmitter, on ssb. Now If I do NOT touch any thing except to slide the transceive/seperate, back to separate when I key the transmitter all is fine,full out. 
 These are new to me ,have had a bunch of kenwoods hybrids over the years, these are the first twins.
anyone have any suggestions as to where to start.? I rang out the transceive cable, checks fine. 
73
dale wt4t