Here is a seaming unlikely thread that talks about a couple of issues with the lps control… I don’t think this is the issue, but could be contributing.
They do state “A level converter on the PWM input at the PSU was not necessary because on 2.75V on average the laser reached 18mA (the max you should go).” which I totally disagree with… one argument is that the IN lps input expect a 0 to 5V ttl type signal… it can also take a 0 to 5V analog voltage. 2.75V is not adequate.
Since it is an average… for a meter to read 18mA at 50% pwm, the peak current (on time) has to be 18mA x (100/50) or 2 times the meter reading. Meaning it’s actually drawing 36mA when it lases …
Without some kind of schematic on how it’s configured and how it’s wired, I don’t know what else to suggest… The schematic, which isn’t, is totally useless as @berainlb has mentioned.
You have two ways to control the lps, they are the IN and the L inputs.
One of them MUST be controlled by the computer … unless you want us to believe you can adjust your controls at the front panel that quickly… 
