TM 9-1290-357-15
Table 4-2. Troubleshooting -- Continued
Item
Corrective action
Probable
cause
No.
Malfunction
Replace vial. (paras 5-12
Foggy, cracked, or
Failure of visual
3.
and 5-44).
broken vial.
indication by the
circular level vial.
Clean, adjust, or replace
4.
Dirty, improperly posi-
Telescope reticle does
reticle (paras 5-21 and 5-36).
tioned, or defective
not become illuminat-
reticle.
ed when a beam of
light is directed into
the reticle.
Adjust objective in cell as-
5.
Parallax in optical
Objective lens incorrectly
sembly, (paras 5-22 and 5-35).
system.
positioned in relation to
the reticle.
a. Adjust eyepiece focusing
6.
Poor definition of the
a. Eyepiece lens cell out of
sleeve.
telescope reticle.
adjustment in relation to
the reticle.
b. Replace defective com-
b. Defective eyepiece assembly
component.
ponent. (paras 5-19 and
5-38).
c. Install reticle properly.
c. Reticle not properly
installed.
a. Replace objective lens.
7.
Poor image definition.
a. Defective objective lens.
b. Adjust focusing sleeve.
b. Incorrect eyepiece,
focusing.
c. Adjust objective cell
c. Parallax in system.
assembly (para 5-35).
d. Install prism properly
d. Improperly installed or
or replace prism.
defective porro prism.
Install the reticle properly
8.
Improper installation of the
Tilt of reticle.
and tighten the loose com-
reticle or loose components.
ponent. (para 5-36).
4-9
