[TenTec] Omni VI TX/RX Frequency discrepency

[keyer]

I have just determined that my Omni 6 Option 3 has a 270Hz difference in 
  frequency between TX and RX. I have a 7040 kHz xtal generator and 
several other rigs to compare things with.
  (much worse than having two watches!)
When the Omni is set to receive 7040 kKz then on TX its actual 
Frequency, measured on another known good rig is 703973 ie 270Hz low.
All measurements were done very carefully on CW, with narrowest filters 
in use.
I assume I can correct this, can anyone point me in the right direction, 
I have the standard TT manual.

Any help appreciated.

73 and seasons greetings to all TT fans

Deni, F5VJC / GM3SKN