You should look at all of your original documentation, to see if there was any mention about spare parts and their availability.
Most agreements like that would be between the companies themselves. Ebay has a thriving market for many spare parts if you were doing the repairs yourself.
Every legal matter is fact specific, and there are often nuances in every case. This is intended for comment only, and does not create an attorney client relationship.
I agree. This should've been provided for in the agreement regarding merger. I welcome you to contact me to discuss how best to pursue this.