Hi Johny,
I bought the 1/2 inch spring washer off ebay. I bought 2 types, 1 was thin similar to the circlip supplied in the washer kit and the 2nd had a wider cross section. I used the first one. Could have done with a bit of filing to make the cross section thinner but once I put it on I could not get if off to do it!
Cheers,
Brett