Damn near impossible to wear out or wreck a leaf spring on a 1911 unless you cut one of the fingers with a file.
You can bend the chit out of them and not hurt a thing other than add/subtract some pounds to your trigger pull.
Likely a 2 minute fix by anyone familiar with a 1911. But if it were me...as I been wrenching 1911s for 35 years as a living, I'd suggest tweak the thing, left side and center forward a few mm and leave the grip safety, right side leaf, alone. Put it back together and test fire. If the trigger isn't resetting it aint the leaf spring.
"he now thinks that the problem may be the disconnector or the recess for same." My thought as well. Again a 2 minute job to fix either or both. That $112 should have covered it all and then some, including ammo and range time.