Fully push the 1st chamber throttle servo pushrod (see relevant paragraph). In this case, the pneumatic actuator of the throttle valve of the 2nd chamber must be under atmospheric pressure.
With the throttle valve of the 2nd chamber closed, measure the gap «Y», which determines its ajar opening, and the gap «Z», defining its cover (see photo), which should be 1.3-1.7 mm and 0.1-0.5 mm, respectively. The measurement is taken at the location of the smallest gap. In case of deviation from the norm, achieve the proper clearances by bending the fork 1.