[Kenwood] TS520S keying

[archie mckay]

I just got a TS520S and everything works fine until I want to operate CW.
The moment I put a plug into the rear CW key jack I get full RF output. This
happens even when the plug is not hooked to a key. Also, I get a steady
tone, possibly the internal sidetone both in send and receive position. I
tried using blank plugs with the same result. Any suggestions?
73, Archie, K4GA