Hitachi ZAXIS 120-6 class Operator's Manual page 405

 Fusible Link (Main Fuse)
In case the starter will not rotate even if the key switch is
turned to the START position, fusible link may be the cause
of the trouble. Remove the cover next to the battery to
check the fusible link. Replace it if blown.
21- + Side (Red)
45 A
22- – Side (Black)
65 A
MAINTENANCE
7-111
21 22
Battery
M1U1-07-023