So a friend brought over his Winchester because the safety is Not Functioning Good. What happens is the bolt will not lock down in the rearward position when the rifle is cocked. All other aspects of the Safety work as they are supposed to. I stripped the bolt down to the shroud; left the safety lever in; and cleaned it thoroughly, put it all back together and no change. If you hold the safety back in the rear position it all works like it is supposed to. The back of the lever does fit flush to the shroud when you hold it back. But one little bump on the bolt and it "pops" forward.... The rifle will not fire when it "pops" forward but the bolt is no longer locked down.
Any ideas what the issue is?

Any ideas what the issue is?