My DH owns a repair and restoration business. He does work with some shippers. He would have been sent to your home to take pictures of the damage, and determine the best method for repair/replacement. It sounds like you need to do this on your own.
You've already found a replacement case, so it you have that covered.
To determine the decrease in value of the machine, he would search the internet for machines with flaws similar to your damaged machine. The difference between what you paid, and the value of these machines would be your damages. Might have to take an average decrease in value, or a percentage decrease in value.
Good Luck