My toolbox has a piece of wire with the last 1" bent at 90 degrees which I use as a dipstick, if there is oil on it there is enough.
My footpump connector is clip on.

Apologies Dave, your reply just got in before mine to Jim ! I'm in total agreement with the bent wire method and 1" level, what do others think ? As far as my electric air pump is concerned, it was quite expensive and I like it but think its one downfall is the 'unscrewing' but again someone may have perfected the art !

Location: Ferring, West Sussex

Hello James.
The question of oil levels is a reoccuring topic on this site. Oil level in the rear axle needs to be at a minimum level that allows the crownwheel to sit in the oil when stationary, but not so high that it could weep past the axle shaft seals. This is about 1/2 to 3/4pt. The cost of rear axles is considerable compared with the price of oil.
So my recommendation, (for what its worth) is don't bother checking the level just drain and refill it with the appropriate amount at regular intervals.
Vince Leek