I will probably replace the washer because I don't want to swap the gasket

[N-OS X-tasy!]

Ammo wrote:
Do you know why the gasket got moldy? Maybe there’s something you could do to prevent that from happening again if you decide to repair it.

When I had one of these washers, I would wipe the gasket dry after every load and leave the washer door slightly ajar to facilitate air drying. Worked like a charm.