Once you start using a DRO (on a mill and/or a lathe), it is hard to imagine life without it, especially for a newbie. If your a seasoned veteran, then the installing a DRO would be a trivial job. I would expect the vendor to make it right, but also the buyer to be reasonable about coming to a satisfactory solution. Installing a DRO is a learning experience, and not an impossible task if your planning on making things and machining. It also affords you the opportunity to install it the way you want relative to the scale locations and the display position. Shipping a machine back, then dealing with the wait and then reshipping would be costly. It would be a real hassle for both the seller and buyer. In my opinion you should either be refunded all costs for the DRO (unit cost, installation and shipping charge as if it was sent separately), have one sent to you at no additional cost (and refund your installation charge), or get a full refund and go to DROPros and buy one of their units. QED.