Washing Machine Leaking from the Front

There is a puddle under the washing machine and you would rather not pay a callout to be told it was the seal. Say when the leak appears and roughly where from. You get a fault tree ordered by likelihood: door seal, drawer overflow, drain hose, pump housing, sump hose. Each comes with how to check it with the machine off and unplugged.

There's water leaking from my washing machine. The puddle appears {WHEN_LEAK_APPEARS} and seems to come from {LEAK_LOCATION}. The machine is a front-loader. Walk me through a fault tree in order of likelihood: door seal tear or gunk build-up, detergent drawer overflow, drain hose connection, pump housing crack, sump hose clip failure. For each one tell me exactly how to check it with the machine off and unplugged, and whether it's a DIY seal-and-clip job or needs a part replacement.