This excavator has been working for three years, and it is still a bad job.

Practice more. For any major, it is tempered by time. After driving an excavator for three years, it is still a plate with two knives, which means that you have not corrected your wrong operation and learned correctly in the process of operation. You need to have a correct attitude, be diligent in learning knowledge and practice the operation of excavators, and you will become better and better.