REPAIR OR REPLACEMENT
Refer to TM 9-254 for general repair instructions.
Repair is by replacement of authorized parts that do not meet inspection criteria. Refer to WP 0134 00.
When maintaining radioactively illuminated fire control equipment, follow radiation
hazard procedures in warning summary (M137 only).
Position optical instrument prism (1) in head housing (2).
Apply a light coat of grease (item 15, WP 0152 00) to new O-ring (3) (item 14, WP 0134 00) and install
in prism pivot (4).
If removed, screw quick release plunger (5) into prism pivot (4) until edge of quick release plunger
thread is tangent to prism pivot diameter.
Install optical instrument prism (1) with bearing aligned over the hole for prism pivot (6).
Use sealing compound in well-ventilated area away from open flame. Sealing
compound is harmful to skin and clothing and may give off harmful vapor. Exercise
care whenever sealing compound is used.
Apply sealing compound (item 13, WP 0152 00) to threads of prism pivot (6).
Install prism pivot (6) in head housing (2) and align with bearings in optical instrument prism (1).
The flats on prism pivot should be properly oriented in head housing.
Shift optical instrument prism (1) to align bearings with pivot hole for prism pivot (4) and install prism
Install plate cover (7) and secure with three machine screws (8).