If it is an FDM printer, it should be encountered: fault, misalignment, warping, and separation of the bottom plate, plugging, remote wire feeding and possibly encountering the Fron tube loose. There is also a tangled material, knotted, very annoying. These problems are not big, but they are annoying. It is easy to play a bunch of wool balls.
Then, if the print quality is not good, the motor will overheat during the printing process, and the torque of the motor will drop, which will lead to lost steps. The structure is not stable, the screws are loose, and the machine shakes too much when printing, which will lead to serious misalignment, reduced accuracy, and even print out, you don't know what it is. If the screw is not straight, it will be tragedy. It is estimated that it is impossible to make a good model.