TM 9-1240-400-34&P
Section III. TROUBLESHOOTING
4-6. TROUBLESHOOTING PROCEDURES.
a. The symptom index can be used as a quick guide to troubleshooting. Common malfunctions are listed in
alphabetical order with a page number reference to the troubleshooting table, where a test or inspection and corrective
action are provided.
b. The direct support troubleshooting table lists the common malfunctions which may be found during maintenance
of the M138 telescope mount. Refer to page 4-4. There are no general support troubleshooting instructions. Perform the
tests/inspections and corrective actions in the order listed.
c. This manual cannot list all malfunctions that may occur, nor all tests or inspections and corrective actions.
DIRECT SUPPORT SYMPTOM INDEX
Troubleshooting
Procedure
(Page)
MOUNTING SURFACE
Mounting surface and locking clamp do not seat M139 telescope correctly ..............................................
4-4
ADAPTER ASSEMBLY
M139 telescope does not hold alinement in deflection...............................................................................
4-4
M139 telescope does not hold alinement with lever locked .......................................................................
4-4
Worm does not move telescope socket 444.45 mils above
or below central position with lever unlocked ........................................................................................
4-5
EXTENSION LIGHT
Light does not operate ................................................................................................................................
4-5
Light intensity does not change when rheostat knob is adjusted ...............................................................
4-5
4-3
