A correction of my last post. The part that I broke was not part of the extruder. It was actually the lower X-carriage. See Below:
When the upper and lower parts of the carriage were assembled the 2 sets of 180 bearings did not close on the steel rod. When I tightened the bolts on that side the two parts of the carriage were drawn together and the lower one snapped. You can see the stress marks where it broke.
When I took it apart tonight I found that it had also broken at the belt clamp mount.
I carefully measured everything that I could think of to compare the original parts that I got from Nophead against the new ones but they seem to be identical. I can only assume that I did something incorrectly during the assembly that threw off the fit but I had completely disassembled it by the time I realized this so I will probably never know. At least I can confirm that Nophead's parts were not the cause of the problem. That comes as no surprise since they have been excellent in fit and quality throughout the build while my own skills have proved to be .............. slightly less than excellent, shall we say?
It only took a half hour to take it all apart and reassemble it. It now fits fine, moves smoothly and I can proceed to fixing my problems with the Z-axis.
I picked up some rubber feet for the bottom of the machine today. They should lift it up enough to resolve my problem with the Z screws contacting the bench and also will help with vibrations. I still have to figure out how to assemble it so that the screws move smoothly. currently the bearings are being contacted by something and won't rotate.