Only send back "defective" merchandise if you have spoken with an Allparts salesperson and he/she has confirmed that the product is indeed defective.
Do not decide on your own that the product is defective; it may be that you ordered the wrong part, or you ordered the correct part but are not using/installing it correctly.
Products returned as defective which are not defective will be subject to a restocking fee and the return shipping charges will not be reimbursed or credited.