I expect replacing the hammer has resolved the growing pull issue.
I agree with Jim, it is likely caused by a soft hammer or sear.
Have you had the opportunity to closely inspect the parts?
A separate comment about pin hole locations.
I layed out the pivot pin holes at ten times normal size to understand the true relationship between the hammer and sear.
Obviously pivot holes not parallel, undersize or worn pins, soft parts, etc, can present problems when tuning triggers.
What I learned is small variations in pivot pin hole placement in the frame can of course change the optimum primary sear pin angle.
The blue prints I have seen indicate the primary sear pin angle to be 90 degrees to the pivot hole.
However to properly match the angle of the hammer notch, this sear primary angle is dressed to be 12-1/2 degrees from the 90 indicated on the prints to match up with the hammer notch at 90 degrees.
This makes the sear tip face parallel with the 90 degree notch at the hammer.
The 12-1/2 degree figure will vary slightly depending upon center to center frame variations and actual sear lengths.
As you know, it takes a rather strong magnification to see the true relationship at the sear pin tip to the hammer full cock notch.
Much more than a typical magnfying glass
This same magnification would be useful to determine if the hammer notch was deformed in any way.
This is my first post on this forum. However, I've been working with 1911's for many years. The blue prints available on the internet and in Kuhnhausen's book have been very informative.
Learn something new each day.