Is it the same for all modes (USB-LSB-CW)? My guess is that it is not. Most
transceivers of this vintage Mix Hetrodyne (band) VFO and carrier frequencys to
arrive at the Transmit or receive freq. The Hetrodyne and VFO frequencys are
the same on xmit and receive. The carrier (mode) crystals are changed to allow
for offset for USB-LSB-CW. My guess is that one of the crystals has shifted.
Use a frequency counter to locate which one and then you will probably be able
to net it via the small calibrating capacitor in the circuit.