JMQ A7 PLUS Instruction Manual page 17

A. Running belt tightening adjustment If the running belt is too loose,
please insert the supplied hex wrench into the adjusting hole of the
left footstep of the treadmill, turn it 1/4 turn clockwise, and then
adjust the right foot to rotate clockwise. 1/4 laps, note that the left
and right must be adjusted synchronously, so that the running belt
can be tightened and the running belt will not deviate from the center
point. If the running belt is too tight, the left and right synchronization
will be adjusted counterclockwise.
Note: The running belt cannot be adjusted too tightly. This will break
the running belt, increase the pressure of the front/rear drum, cause
damage to the roller bearing, etc., abnormal noise or other problems,
and only need to adjust to the running belt without slipping.
B. Running belt alignment adjustment
When you use the treadmill, the pressure on the two belts is not
the same when running, and the pressure on the running belt is
unbalanced, causing the running belt to deviate from the center. This
deviation is normal and it automatically returns to the center when
no one is running on the running belt. If you don't get back to the
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