[Elecraft] Help,advise K3/KPA500 problem

[r miles]

They have been humming along for  a yr. I'm not computer savy so with 
help from my friend Jamie I was up and going. Three days ago my 
outboard keyer died. I pulled the K3 forward on the desk to plug in  my 
spare keyer. [I prefer an outboard keyer]. When all was connected & the 
radio pushed back in position the K3 & KPA500 are not talking. I get no 
message on the K3 display the KPA is on. The amp is just bypassing RF. 
The KPA displays the K3 output power but when I key the amp sits in 
standby.The band following is not working. They just are not 
communicating. Jamie suggested unplugging all the interconnect cables & 
reinserting them in the K3 & KPA. Maybe a lost connection.
That had no effect. I'm open to suggestions as a starting point or if 
anyone else has experienced this & how they resolved the problem. I want 
to get the KPA going as I have a new KAT500 in a box on the shack floor.
TNX
K9IL