TM 10-3930-659-20 17-4. HYDRAULIC CYLINDER DRIFT/LEAKAGE TESTS (Con't). 6. Start engine (see TM 10-3930-659-10). 7. Raise and lower carriage assembly (5) a few times and position carriage assembly 3 ft (1 m) above ground. 8. Shut down engine (see TM 10-3930-659-10). 9. Measure   distance   between   bottom   of   carriage   assembly   (5)   and   ground.      Wait   one   minute   and   repeat measurement.  Record change in distance. 10. Wait 10 minutes and repeat measurement in step 9.  Wait one minute and take measurement again.  Record change in distance. 11. Compare changes In measurements in steps 9 and 10.  If drift is same for each of the two one minute periods, replace  forklift  control  valve  (see  paragraph  17-8).    If  drift  is  less  for  second  one  minute  period,  replace fork/boom cylinder (9) (see paragraph 17-32). TA707620 17-15