The STL is for an axle about 5mm in diameter and a mounting shaft about 6.5 with a retention detent near the end.Take a look at the scad and adjust axle and mounting shaft sizes if needed, print, pop the old wheels and shaft on.
I'm a computer person who grew up on a farm. I enjoy all kinds of making. Programming, electronics design, rough carpentry, whatever.I am a mentor for FIRST Robotics FRC team 1502, "Technical Difficulties" at Chelsea High School.