I just realized that my 870 barrel has lost the "spring detent ball?" There is only an open hole and the mag tube band. Has this happened to anyone else? Where do I find the parts to remedy this? I will call Remington on Monday, and I would guess Brownells would have them, I just hate to order $0.02 worth of parts. Why did this happen? BTW, the gun was broken down into two pieces in the green Remington plastic case.