TM 10-3930-671 -10 b.  Hydraulic Fluid Service. CAUTION Do   not   overfill   tank   with   hydraulic fluid  or  serious  damage  to  hydraulic system may occur. (1) Check hydraulic fluid level (para 3-10 [a]). (2) Remove   hydraulic   sump   breather   (1)   from   fill tube (2). (3) Add oil to hydraulic tank until hydraulic fluid is at correct level (para 3-10 [a]). (4) Install  hydraulic  sump  breather  (1)  on  fill  tube (2). (5) Check hydraulic fluid level (para 3-10 [a]). 3-21