cupped washers needed

[ed1965dream]

After not finding time most of the summer to work on the Dream I'm finally getting back to it. When I last worked on the assembly I was looking for a source for the cupped washers or so called dust shields that go in the front cushion. (51333-250-000) As the Dream came to me in boxes, I only have one of the 4 required.

I've searched around the world for these washers and came up with nothing, so I'm wondering is a flat washer would work ok. I believe there is a felt seal that goes in the cupped washer to protect the bearing that completes this part. Anyone ever use a good substitute for these? It's a little amazing that a part as small as this is holding me up. Thanks