To receive your core refund1, all cores must be returned in the original box with your original receipt from Shop Parts and be in re-buildable condition. Customer is responsible for any shipping charges incurred for return of "core valued" items.
Before returning your core, be sure to drain fluids (excluding batteries) from the core and place the latter in a plastic bag to prevent leakage. Then pack the core in the box that contained the new part you purchased from Shop Parts.
1 No tax refund on cores