[Luddite]

A second pair of hands is definitely useful for this! Do you have crocodile clips on your meter leads? Try attaching them to the contacts if you have the room, which will keep your hands free to turn the wheel. (Note - if you're spinning the wheel by hand, you probably won't see much more than 0.5v on the readout.)

Alternatively, if you can attach the meter to the plug securely and the leads are long enough, try resting it on the tank and ride the bike slowly up your drive while checking the meter.

By the way, if you find you need a replacement, the part no. is 55212121B.