I found that a He-Ne laser which has been used for ETMX_OPLEV was NOT giving the light.
Since I didn't find the switch key for it I have no idea if the laser is simply off or dead.
The dead laser was replaced by new JDSU 1104P of 2.6mW. The return beam is big ~5 mm diameter of 0.3 mW, 1400 counts
Whenever replacing any Oplev laser, please also put into the ELOG when it was installed so that we have an electronic record of the laser lifetime.