"Standby compass swings are done with the gear lever solenoid in the flight condition. Most pilots and compassswinging people know not to operate the gear lever during a swing, but we leave the landing gear locks fitted just in case "
Not sure I understand, this, Blacksheep...
Moving the lever is not going to activate the solenoid. The air-ground system does this (in response to gear tilt).
Also... usually the lever lock solenoid is activated by one of the main DC busses. If you've got these, chances are you've got main AC busses, too, to drive the instrumentation. Why would you need to calibrate the compass in this configuration?
Perhaps moving the lever to it's normal flight position is simply because you have moved the lever mechanism (metallic, mechanical part) to a different location?
Rgds.
NSEU.