Place your shallow pan and towels directly below the filter. Even a "drained" machine holds 1-2 gallons of water.
Once the water stops, pull the filter out. You will likely find a horror show of coins, bobby pins, sock lint, and dog hair. Clean it thoroughly in a utility sink. how to unclog washer drain
Give yourself a high-five. You just saved $150–$300 on a service call. Now go finish that laundry. Place your shallow pan and towels directly below the filter
Shine your flashlight down the pipe. Can you see standing water? If yes, you have a clog. You will likely find a horror show of
Use a flashlight to look inside the hole where the filter was. You may see a plastic fan (the impeller). If it is jammed with debris, use needle-nose pliers to carefully remove it. If it spins freely, you're good.
Once you feel the snake push through (it will go in much easier), pour a kettle of boiling hot water down the pipe to flush out the remaining debris.
Insert the plumbing snake into the standpipe. Crank the handle while pushing down. You are trying to break up the blockage (usually a mix of lint, soap scum, and fabric fibers).