Page 53 of Hydrostatic Operator’s Manual:

BELT ADJUSTMENTS

Pump Belt and Final Drive Belt

The pump and final drive belts are adjusted at the same time because the adjustment of one effects the other. The pump belt is tensioned until it has a deflection of 1/4″ to 3/8″ at the center of the belt. The final drive belt is also tensioned to a deflection of 1/4″ to 3/8″.

To adjust, loosen the pump bracket attaching bolts and the final drive idler pulley adjusting nut. Back off the pump adjusting bolt lck nut and tighten the adjusting bolt until the bump belt is properly tenionsed (1/4″ to 3/8″). Tighten the lock nut on the pump adjusting bolt and the pump bracket attaching bolts. Tighten the final drive idler pulley adjusting nut until the belt is properly tensioned (1/4″ to 3/8″).

WARNING: Excessive pump belt tension may cause rapid bearing failure and/or belt deterioration.

ADJUSTMENT NOTE: Start the carriage moving in a forward motion and hold onto the engind shroud handle with one hand and the engine tightener with the other hand. Brace yourself with one foot on the lower portion of the track. In this position, you should be able to just stop the carriage (the final drive belt should slip to allow this). If little effort is needed to stop the carriage, then the final drive belt must be tightened as it is slipping too much. Tighten the final drive idler pulley adjusting nut a few turns and recheck.

Hydro Belt Adjustments << See the manual page and illustration here.