I am not where I can lay hands on the 15Y in the safe, but a couple of things to consider-
There was a design change about 1992 that changed the ejector- and the early one was not in the bolt- it was a little doo-dad on the receiver that slid thru a slot in the bolt to eject an extracted round- basically the bolt slid back onto a small post that popped out the fired case.
IIRC, they had a habit of breaking off, which lead to the design change.
And before you buy a bolt, there was a 15Y and a 15YN, not quite same thing. And when replacing a bolt, is ALWAYS a prudent thing to have headspace checked by a smith. 99 times out of 100, no problem. But that 1 out of 100 will be a very exciting event.
With the rifle unloaded, raise bolt handle, shine light into opening, slowly draw bolt to rear. As it reaches full withdrawal, you should see little bit of metal appear on far side of bolt face- that is ejector (not to be confused with extractor, which just pulls fired case out of chamber) If you no see, there's yer problem.
You might also try calling Marlin Tech Services.