I had fun and games trying to find an O ring for the fork tops because both were leaking quite badly. Never did find them though and Yamaha don't sell them separately and a replacement fork top is £yike.
As it turns out, I didn't need them because the problem was corrosion in the fork top. I had my fork tops level with the yoke, so I presume salt water had sat there and and over time worked it's way in. I've got the fork tops just a couple of mm above the yoke to prevent it happening again and of course a bit of the ol' red rubber grease around the seal.
Before you do anything, whip the tops off and see if there's any corrosion. Even the smallest spec of dry white aluminium oxide can cause the leak. Rubber + corrosion = zero seal.
