There's nothing special about the washers. I have some here in front of me. The id is about 3mm. The od is about 7mm. These measure about 0.7mm thick with my caliper.
Another way to measure; I have a colored pencil with a flat unsharpened end (Crayola brand - light blue). The diameter is about the same as a regular pencil, only round. I laid the washer on the flat end. The washer is almost exactly the diameter of the pencil, and the hole is almost exactly the size of the colored lead. Don't worry about the thickness. Any washer that size should be close enough.
Go to the hardware store and buy them.
Cody
