1. Update all firmware, autotune PID and retest

2. If error persists, swap the left and right interchangeable hotends and retest

3. If error moves to the right, we replace the broken interchangeable hotend 

4. If error stays on the right, swap the left and right hotend adapter board cable as shown below and retest:

5. If error moves to the right, we replace the cable

6. If error stays on the left, take off the hotend controller board shown below and measure the resistance of the fuse:

7. If it shows OL, we replace the board.