That's a new one on me. I'm not sure that I'd trust the knurling to keep the lobe from spinning permanently. Once it spins, you're dead in the water. If you can't figure it out, it may be time for an electric pump. One more thing after all that, did you happen to install the lobe backward? I'm just wondering if it will spin after being installed backward. Did you happen to forget the cam retaining plate and that let's the eccentric go back too far? It's been a while, but I seem to recall that the eccentric sits over the key. Not behind it.