Changing the o-rings on the heater core.
My question is if the clips will push the o-rings (and tube) into the seat or do I need to get the tube seated before the clips will go in. Any suggestions on how to get the tubes seated if that is what I need to do?

Also, I had pull the heater core out slightly to get the lower clip out. It ran up against a piece of plastic.

Both clips came out towards the back of the vehicle. Is that where they are supposed to go, or did someone put them back incorrectly?