Dear 1911 has it right.
I just serviced an XT that has been through three owners and years of abuse, before it starting having problems digesting shells through the bottom barrel.
The amount of goop in the action was as bad as I have seen in years. The firing pins looked like they had been on the head of the Space Shuttle during re entry.
After a routine service, and replacement of firing pins, lower return spring, left standard mainspring, right Wolff Extra Power mainspring, and Top Lever spring, all was well again.