seems like its when you buy a part you get an extra charge called a core charge. its returned when you return the part after its broken.
the reasoning is 1) incentivize ppl to return stuff for remanufacturing/refurbishing 2) lowers the price of the part since the manufacturer can rely on a influx of old parts they can repair and resell for cheaper vs making a completely new part
whether or not its a reasonable idea/done properly aside, if you can repair the part and get more lifetime out of it, that should still be eligible for core refund when you do finally return it, no? i dont see how a core charge refund disincentivizes you from repairing the part when you have to get a replacement one anyways if you dont repair it.