LaserUser.com Forum (formerly RDWorksLab)

This is normally caused by the beam hitting the nozzle [not centered in the nozzle hole] which causes a reflection in one direction.

Mine was doing that also. It started after I used a q-tip to clean the lens. Apparently I must have loosened the retainer and the lens was vibrating. So I took it apart and cleaned the lens properly then tightened the retainer and problem was solved.