I had a brand new 77/17 with the same problem. The fixed standing ejector is part of the trigger guard assembly. On my rifle the tip of this ejector had been ground down too far (by the factory) and allowed the case rim to ride over it instead of being pushed off the bolt face. I think this may be your problem. Take a close look at this area as you extract a case. You may even find that pushing downwards on the front half of the bolt as you extract is enough for the ejector to engage properly with the rim.
In my case the shop swapped the rifle. In your case (if this is the cause), a small weld bead on the ejector tip and some filing to shape would be a solution.
