TM  10-3930-669-20 15-22. MAST AJUSTMENT (CONT). NOTE •    Perform steps (8) through (13) if mast assembly is uneven. •    If mast assembly is uneven, shim the lowest side. WARNING •    To  avoid  personal  injury,  use  a  hoist  or  get  assistance  when  lifting  components  hat  weigh more than 50 lbs (23 kg).  Ensure all chains, hooks, slings, etc., are in good condition and are of correct capacity.  Ensure hooks are positioned correctly.  Always use a spreader bar when necessary.  The lifting hooks must not be side loaded. •    Keep clear of equipment when equipment is being rais ed or lowered.  Equipment may fall and cause serious injury or death to personnel. •    Do not work on any item supported only by lift jacks or hoist.  Always use blocks or proper stands to support the item prior to any work.  Equipment may fall and cause injury or death to personnel. (8)   Remove screw (11) from top of intermediate rail (12). (9)   Start fork lift (TM 10-3930-669-10) and raise mast assembly (2) until intermediate rail clears the top of stationary rail approximately six inches (152 mm). NOTE It  may  be  necessary  to  pry  the  secondary  cylinder  rod  out  of  the  intermediate  rail  top  cross member. (10) Block the intermediate rail (12) in position and lower secondary cylinder (13). NOTE Each shim is .050 in.  (1.27 mm) thick. (11) Position shim (s) on top of secondary cylinder (13). (12) Raise secondary cylinder (13) and install screw (11) into intermediate rail (12) and secondary cylinder. 15-80