Notes about our home repair.
The master bathroom and downstairs bathroom use Price Pfister 7G-1H and 7G-1C water faucets.
Turn off water below the faucet. (Of course! But also so you can do the next part.) Then open the tap when you unscrew the step. A closed tap seems to create a vacuum or hydraulic counter pressure.
The inner O-Ring is Danco's #8 (AS568B# 110). It's 9/16" OD x 3/8" ID x 3/32".
A leak at the faucet is probably caused by the seat washer. The Danco 80359 (fits 3H-8H/C) seems to work.