The left front fork has continued to leak on my YZ426. I could not find any scratches or marks on the forks. I had a shop replace the seals and fork oil. I rode the bike once and it leaked again. I returned the bike to the shop and they replaced the seals again. After that repair, the forks did not leak until I had ridden the bike a couple times. Any ideas on the cause? Could it be the bushings or faulty work on the shop?