The laser tube has a finite service life.  Some problems may happen sooner and some even are not problems, though they appear to be. Use the list below to troubleshoot your laser tube that might be acting weird. 

Abnormal colors of laser beam (normally pink)

Purple-ish beam>>

Whitish beam>>

Reddish beam>>

Split beam/Beam shift in the laser tube

Split beam inside the laser tube>>

External laser spot split>>

The laser beam hitting the cathode metal ring>>

Beam instability in the laser tube>>

Unaligned Laser beam>>

Reduced laser power>>