new proportioning valve leaking

I just spoke to Chuck at Inline Tube [Edit: as stated above, I was mistaken when I thought Inline Tube was the manufacturer]. He says it happens "2 or 3 times a year" and they would send me a new one...if I had bought it from them or one of their authorized vendors. (Unfortunately I bought it on eBay from Dr. Diff who apparently is not one of the authorized vendors.) Chuck also said replacing the crush washer is an option but as OKDart suggests, it's hard to find the right size washer. I'll see if Dr. Diff can help me out.