The reference adjustment time for successful spindown is 40-60s (not absolutely).
Time ≥60s means the belt is too loose. Please power off the trainer to cool down, then power on the trainer and ride it for 10 minutes. Then perform the spindown by clockwise rotate the 3mm screw half round to tighten.
Time ≤40s means the belt is too tight. Please power off the trainer to cool down, then power on the trainer and ride it for 10 minutes. Then perform the spindown by anticlockwise rotate the 3mm screw half round to loose.