I built this tricopter last year. The first few flights were a complete disaster!

The tricopter was virtually uncontrollable and took a lot of fighting with the sticks to get it in the air at all. No amount of PID tuning helped at all.

At first I thought that I had damaged the flight controller as I had had a lot of problems flashing the firmware on the Illuminati 32s. I decided to leave this one and use it for parts in a future project. 

During the current coronavirus lockdown I thought I would have one last look before dismantling it. It was only then that I noticed that one of the spars was slightly warped and the port motor was not level.

A couple of washers under the motor mount soon had the motor level.

I reset the PIDs to default, checked all the Cleanflight settings, recalibrated the accelerometer and tried another test flight. Hey! It flew great. After a bit of PID tuning it is now one of my most stable copters.