Milwaukee regulator help

[props]

k i'm puzzled
my co2 tank ran out couple of days ago so i bought myself a 20lb co2 tank.. with the main valve off i turned the main black knob so that its loose and also turned off the bubble counter adjuster.. turned main valve on and great 65kg/cm² @ main guage for main pressure.. adjusted black knob for low pressure use and set second guage to 10lbs/cm².. plugged in the solenoid and hurray bubbles started coming out so i tuned it down to 65bpm.. works for two minutes then all of a sudden bpm slowed down till it stopped after roughly three minutes.. whats the deal? broken solenoid? low pressure? or too much pressure?
i have adjusted 2nd guage from 2lbs/cm²-25lbs/cm² but same result
help pls

heres what it looks like