Maybe you don't need a new seal yet. I had a leaky fork seal on my TTR (but it has WR450 USD forks on it). Cured the problem by running an old credit card around the fork between the seal and the slider. You hold the card flat against the fork slider and slip the corner of the card between the slider and the seal. This is a trick my local workshop taught me. Seems to remove whatever bit of dirt is causing the leak or perhaps straightens out a folded over lip in seal (?). Anyway, worked a treat.