First thing is disassemble the cylinder and find out where it is binding. It could be in the extractor center hole or the extractor rod. If the plater did not adequately neutralize, dry, and oil the parts before assembly there could be rust inside the extractor rod. It would be unusual for there to be so much plating as to cause the problem. It could also be improperly assembled.
If it is rust the solution is obvious. If the extractor was plated (it shouldn't have been) and this is where the problem is, you will have to obtain a reamer of the correct diameter and ream the extractor hole. This is a critical dimension, don't use a drill!
If the plating in the extractor rod is the problem then either the extractor rod will have to be reamed or the centerpin polished until it is free in the extractor rod. Note: The diameter of the centerpin in front of the integral collar (spring seat) is not critical, reducing it .001-.002" will cause no harm, although using the correct sized reamer inside the extractor rod is the better solution. The back end of the centerpin is critical as it would affect locking and timing of the cylinder, this must not be reduced.
Let me know if you don't know how to find small reamers of a specific size. One should cost somewhere between $6-24 depending on source.
