the hole depth between the plastic lower and metal lowers is different...the metal is shallower.
when swapping you can either leave the screw collet proud a thread or two...or grind the bottom of the pin down about 3 mm and it'll fit.
that's assuming you can get it out. if you can't get it out, you can use a screw driver that has had the middle section ground out...a split ring plier....a stiff small needle nose plier...you can nudge one side, then the other...basically whatever will work to get it started to unscrew for a thread or two.
........or you can mangle it.
