The top jaws are American Standard tongue & grooved top jaws. I see them on eBay and other sites for sale. Prices are all over the place. Expect to pay around $100-150 for a new set of top jaws. For $125, you can have a new Asian built chuck with tongue & grooved jaws. So, do you tie up more money in a used chuck? or tie it up in a new chuck? I would suggest getting a set of soft jaws to use on this chuck, where you are running a bunch of part of the same, and bore out the jaws to match the part for zero runout. Your call on what to do.