I didn't know where it was on my engine until I read a thread yesterday with a pic. So I was looking at mine for s & giggles and see that the center "knob/shaft" is loose. It was out about a 1/4" and I pushed it in. I'm wondering how long it's been loose and if it can fall out. Why would it be loose anyway? What do you guru's recommend? I plan to ride tomorrow. Thank you!