I have used an o-ring in place of the fibre "shim" in the past to get me going. The needle bearing seems to outlast the deep groove ball bearing on the other side by a factor of 2 or 3 to one for me anyway, there are no proper seals for the ball bearing it relies only on its own dust seal not really good enough, so it may be a good idea to plug up the void behind the plastic cap with waterproof grease just as a little extra water barrier. Good little thread there OP thank you.