Place torque wrench adapter (1) on torque wrench (2) and place over knob (3).
Measure torque. Torque required to move diopter scale should be between 2 in.-lb (0.23 N-m) and
5 in.-lb (0.57 N-m).
Use cleaning compound in well-ventilated area away from open flame. Cleaning
compound is harmful to skin and clothing and may give off harmful vapor.
If above torque cannot be obtained, apply coat of grease (item 16, WP 0152 00) to threads to increase
torque or clean threads with cleaning compound (item 12, WP 0152 00) to decrease torque as necessary.
If torque still cannot be obtained, return M138/M138A1 elbow telescope to depot maintenance.
Illumination Inspection - M138 Elbow Telescope
If not illuminated, follow radioactive safety precautions in warning summary.
Take M138 elbow telescope into dark area and wait 15 minutes. Look through eyepiece and check that
illumination is present and even.