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Good observation. The places where the screws go through a part (like the tibia sides) are all sized 3.00mm and the places where the screws go into a part (like the tibia spacer tube) are all sized 2.26mm in my Fusion360 CAD. The smaller size is done to give the screws some "meat" to grab onto when driving them together. I experimented with the 2.26mm dimension and found it worked well for PLA and the 4-40 screws I used. Another option for you might be to simply drill out the 2.26 holes to something slightly larger - like 2.5mm if you can find a drill bit in that size. That might work so you don't need to order new screws.