The shoe appears to look like the 15-121 shoe. I have tried the 15-067 shoe which measures 9/16" thick. The 15-067 does not lock. Measuring the 15-067 to the old shoe, the original shoe appears to be 1/16 inch thicker than the 15-067 so the old shoe is 5/8 inch thick. By chance, do you also have a spacer shim? Just in case?
Does this shoe have a "brake" so that it will hold its' position so that the window can be installed or removed when pivoted?