The bearing seal is identified as 50mm x 100mm x 13.5 mm (shaft diameter x outer diameter x thickness). Doing some online searching/research, I don't find that exact specification. I do find 50mm x 100mm x 10mm.
Looking back at MattL's thread from his project, the "Handyman" guy sources a 50mm x 100mm x 10mm seal. Hmmmm.
Also interesting. Parts diagram for "current" Duet model WFW9151YW shows the spider available as a separate item. An online source lists it for $87.48. However, GHW9400PW4 is the model at hand, which lists a different complete drum than WFW9151YW, so I don't know if perhaps the drum sizes are slightly different or 9151 mounts the spider differently, or something.