TM  10-3930-638-24&P 2-41.   BRAKE   SYSTEM   TROUBLESHOOTING   (cont) MALFUNCTION TEST  OR  INSPECTION CORRECTIVE ACTION 4. SERVICE BRAKES GRAB (cont) Step 6. Check wheel cylinders for leaking condition or sticking piston (para 2-43a, step 1). a. If wheel cylinder is leaking or piston is sticking, replace wheel cylinder (para 2-43a). b. If wheel cylinder is okay, reinstall hub and drum assemblies and axle shafts (para 2-39f), lower axle and wheels to ground, remove shipping lock pin (store under operator’s seat) and remove blocks from wheels. Replace or repair hydraulic brake valve (para 2-43c). 5.  SERVICE  BRAKES  SQUEAK Step  1. Place blocks (6 by 6 by 18 inches wood blocks) at each wheel to prevent vehicle from moving, Remove  shipping  lock  pin  from  storage  area  under  operator’s  seat  (para  2-4b(1))  and  install  in  chassis. Ensure that parking brake is in applied position. WARNING Before raising axle off ground, be sure that shipping lock pin is installed. Failure to do so may cause vehicle to turn and slip off jack or jack stands causing serious injury or death. If you are in- jured by falling equipment, obtain medical aid immediately. Raise one axle and wheels off ground. Remove  axle  shafts  and  hub  drum  assemblies  (para  2-39f). Check brake linings for wear, uneven wear, glaze, brake fluid or lubricant contamination, and/or exces- sive dust. Repeat  for  other  axle  and  wheels. a. Replace brake linings that are worn, glazed or contaminated; remove excessive dust (para 2-43a). b. If brake linings are okay and there is no excessive dust, proceed to step 2. Step  2.  Check  hub  and  drum  assembly  for  scored  condition  (para  2-39f). a. If hub and drum assembly is scored, replace brake drum (para 2-39f). b. If hub and drum assembly is okay, check for damaged brake shoe return spring (para 2-43a); replace brake shoe return spring (para 2-43a). 6.  SERVICE  BRAKES  OVERHEAT Step  1. Check  brake  pedal/return  spring  linkage  for  binding,  interference,  missing  parts,  or  damage  (para  2-43e). a. If brake pedal/return spring linkage is binding, has interference, is missing parts or damaged, re- pair  or  replace  (para  2-43e). b. If brake pedal/return spring are okay, proceed to step 2. 2-264