Like tmarks11 said, don't check the collet chuck parts, check a known straight, round, and parallel part, like perhaps a dowel pin, mounted in the collet chuck and see what you get then. Try different diameters, because collets also have runout. Also, does the collet chuck have an integral D1-4 mount or does it have a separate back plate that mounts to the spindle? Make sure that the back of the back plate or the integral D1-4 mount is sitting dead flat against the spindle when it is tightened down. Check it carefully with a light from behind. Also make sure that there is at least a bit of interference fit between the spindle taper OD and the collet chuck or back plate ID taper. If the taper fit is too loose you will have radial runout. If the chuck is not pulling completely down on to the the spindle face it will not be square with the spindle and you will have a wobbling runout. You want to be snug on both at the same time without gronking down on the square keys. Also make sure the lathe spindle itself does not have runout on the taper or on the chuck mounting face.