[64catdroptop]

If you can't push down on the hood to close the gap, then there is obviously an obstruction.

1. Remove the air clearner and hood bumpers (even though you say they're prefectly aligned and don't touch - see of you can close the gap by applying pressure on the hood nose) I would also remove the spring and safety latch from the hood to see if you can get it to close completely - then re-install one by one to see if you can determine the problem.

2. I do see a slight difference in the hood release height of the two nose pieces you show - that may be the problem - additionally, the one has a tab protruding upward while the other doesn't. Furthermore; the hood release's seem to be at different angles (view from top) and are also of a slightly different design.

3. Bruce may be correct in that the hinges being the problem - oil them/adjust them if necessary - but usually the problem with a bad hinge or poorly adjusted hinge is the rear of the hood doesn't close/come down completely