I just finished reading a long thread on HKPRO comparing the HK45 and Sig 220. After reading that thread, and several threads at the Sig Forum, there seems to be a lot of complaints about extractor issues and feeding problems with many of the Sig 220s.
This played a part in my consideration of skipping the Sig and getting the HK45 today.
From what I have read, you will have to contact Sig and send them your gun. This issue seems to revolve around the 220 Sigs over other models.