McMaster-Carr has replacements, I just put new washers in mine due to the rust. The M-C washers are found under the listing of Belleville (sp?) washers. The ones I chose were stainless steel so won't have to worry about the rust. They come in packs of 12 so I bought 2 packs since there are 16 washers required. The part # is: 96475K346. $9.67 per. 2 required. Shipping is $7.50 usually. Pretty fast, UPS.
The dimensions are: 10mm I.D. 20mm O.D. 0.9mm thick.
I also have some new black flange nuts if you would like I can mail you some. They are not acorns but I couldn't find them anywhere. These work perfectly and are not visible when installed. Had to buy a bag of them so I have extras.
Hope this helps