EOTech CNVD-T3 Clip-On Night Vision Device - Thermal 3 - Manual (Page 56)

3-4
NOTE
A slight, audible hissing sound may be noticed
during the venting process as air escapes from the
purge port.
(3) Gently rock the purge screw back and forth to
vent the CNVD-T3.
CAUTION
Over-tightening the purge screw may damage the
CNVD-T3 housing.
(4) Reinstall the purge screw and tighten until
snug. Once snug, turn the purge screw an
additional 1/8 turn to tighten.
e. Poor or degraded image.
(1) Perform a calibration per paragraph 2.13.3.
(2) Remove night adaptive filter / demist shield, if
installed. Clean eyepiece and objective lens.
(3) Inspect the night adaptive filter / demist shield
for dirt, grime, scratches, and cracks. Clean
and/or replace, if necessary.
(4) Replace existing batteries with fresh batteries.