It is possible that during the transport, height of the nozzles (left vs right) becomes slightly different. This can cause unwanted effects during 3D printing when lower nozzle could touch and mess up your print.
Keeping both nozzles on the same height is also important when printing the first layer of your 3D model as it affects its adhesion.
If you want to make sure that both nozzles are correctly positioned, home all axis (Home to center), clean the nozzles, and inspect the gap between them and the glass printing surface.
Place a thin piece of paper between both nozzles and the heatbed. Both of them should cause the same friction. If one of them is more loose or you can visually see the difference, then you should the calibration procedure described below.
Home all axis to center. Make sure that the glass printing surface is flat and clean. The same goes with nozzles. You can heat them up for cleaning, then switch off the temperature for calibration (choose Filament Menu >> Cooldown on the display screen).
Try to loosen 2 screws shown below. Usually 1-2 turns should suffice.
With the nozzles loose, perform Z-regulation. Adjust Z-endstop, so nozzles touch the table. Both hotends should adjust themselves vertically and level up.
Tighten the screws back to their original positions. Turn them back the same number of turns as when in step 1. Strong force may be required but this will keep the nozzle tips at the same level.
If you still have problems – you should repeat the entire operation.
Please note, that if you don’t feel confident with precision mechanics and your technical skills, you can just send the extruder to us. We can perform the calibration for you and ship it back.