There are also metal bushings that go inside the rubber washers.
The new ones were a little shorter than the original ones.
If you get some sheet rubber the right thickness, you can make your own washers for a fraction of the the ridiculous price from MF.
Use a hole saw, to cut them out of the sheet.
And yes, you can replace them without taking the wheel off. It is tricky, but possible.
One helpful hint is to use something sticky to attach the washers, and the bushings to the rubbers. I used a very small piece of butyl tape. Then, you fish the washers into place with anything that gets it done. Once in place, use an awl, or thin metal punch, or rod to align everything with the hole.