[G6Tanuki]

"I used a digital receiver to listen to the local oscillator which is a very easy way to get the end points spot on - on most receivers anyway. Even easier than a frequency counter apart from the mental maths involved. "

Agreed 101% - when frobbing around with this sort of thing I find a modern digital-synthesized receiver to be much more useful than a frequency-meter: you program one memory of the 'test' receiver to the "lower set-point" of the receiver-on-the-bench's intended LO when tuned to the lower alignment-frequency, and another memory to the LO 'upper set-point' alignment frequency.

Also program the 'test' receiver to CW.

Then it's dead easy: set your test-receiver to the lower-set-point memory, tune the receiver-on-the-bench to its lower-set-point on the dial, and twiddle its coil slug until you hear the whistle on the test-receiver.

Switch to the higher-set-point memory, tune the receiver-on-the-bench to the appropriate calibration set-point on its dial, and tweak its capacitor until you hear the whistle.

Repeat this a few times: because you've stored the two points in your test-receiver's memories it's quick and easy to toggle between them.

My current 'test' receiver is a Yaesu FT897D and out-of-the-box its calibration's a lot more-accurate than any of the surplus 1980s/1990s H-P or Rohde&Schwartz frequency-counters/sig-gens I've had in the past.