The crusty looking images are the original part being replaced. I redesigned the original piece to make it easier to print and eliminate some odd design flaws that lead to the part failing in the first place. It should fit both round and hex bolts perfectly. This piece should be printed solid at .15 mm layers for maximum strength (0.15mm also allows the grove to print with no overhanging layers and no supports). The part should not be printed on regular pla. Even then, I cannot vouch for the longterm durability of the piece. If you have access to the materials and capable printers I would highly recommend printing in nylon, asa, or polycarbonate for this piece. As it stands I printed versions in petg and voxelpla pla pro which is the toughest filament I have access to at the moment. I may make a version 2 that is multiple pieces printed in different orientations and then glued to optimize for layer strength.