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Prior to assembling the extruder, check that your x-axis belt fits into the x-carriage. If it cannot be fully inserted, it is probable that your printer is over-extruding. Check/reduce your EM, if you find it impossible to insert the belt fully.
When checking the printed parts, check that your x-axis belt fits correctly in the x-carriage. If your printer is correctly calibrated, the belt will fit properly. If you have difficulty fully inserting the belt, check your extrusion multiplier and reprint the x-carriage.
Just to clarify your misconceptions, Gates Unitta is the Asia wide joint venture between Gates Corporation and Nitta Corporation. They manufacture and supply genuine Gates parts, including 2GT belts and fittings. Gates LLC (US/Europe) no longer make 2GT belts or fittings.
So E3D source their, genuine, Gates 2GT belts and parts from Gates Unitta. Anyone wanting to supply Gates 2GT belts (eg. Prusa), will have to source them from Gates Unitta.
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