On the original Icom 756 it is possible to calibrate the radio EXACTLY
on frequency with no tool more exotic than a small screwdriver. You may be able to adapt this idea to your rig.
By the numbers:
1) Warm up the radio for 30 minutes or better.
2) Set the RX mode to AM
3) Turn on the internal 100 kHz marker / calibrator
4) Tune WWV to whichever frequency is strongest and has the least QSB
5) Adjust the master oscillator trim cap through the hole in the lower front right cover for exact
zero beat *
6) Turn off the internal 100 kHz marker / calibrator
* When approaching zero beat the audio will go sub-audible. Observe the S-Meter. It will oscillate slowly then hold steady at exact zero. It takes a good hand to tweak to exact zero, but don't worry about being off slightly as the adjustment will drift a tiny bit with temperature. There is no shame in being off by three Hz.
Ten Hz, yes, the other guys in the net will start calling you Vinnie. But three Hz? Not so much.