Hi, I just picked up a 600/Open Pro wheel set for $10 and felt all smug, but then I noticed that whatever is supposed to cover the bearings on the free hub side is missing :-( Is this just a dust cover that could be improvised? I was looking at the exploded diagram and it appears that #15 is the cone, which is there, so I wasn't sure what I was looking for. My friend is always mocking me for bringing home borderline garbage bike parts, so I'm hoping to get these rolling without spraying grease everywhere to prove the wisdom of my frugality.