Staff (YIS) reported air hissing sound between rear M2 and rear M1 car. Staff(YCK) checked and confi rmed heard the air hissing sound between B2 and B3 door. ~~~~~ 2556 Staff (YIS) reported air hissing sound between cars. Staff(YCK) confirmed heard the air hissing between B2 & B3 door.  2556 bogie #1 B/S levelling v/v connecting rod broken. Replaced the connecting rod with spare. Adjusted #2556 bogie #1 carbody height : A/S = 853 mm, B/S = 855 mm Function check - OK. Air leak test = 0.5 bar/5 min (Initial leak rate : 1.2 bar/5 min).  Kana 44389