[TenTec] Triton IV PTO warble

[g p]

Had a few of these in the past but I have never encountered a warble and of course it is more pronounced on CW even when not touching the tuning knob, in other words I can tune in to a station, leave it there and the warble just goes on and on, there is no drift and the tuning is very smooth. 
 
I have not gone inside the rig yet but before doing any surgery on it I was planning on tightening the boards first.
 
Any input on this appreciated.
 
Thanks, Gil