My first Milwaukee MA957, crapped out on me in about 2 weeks into using it, the solenoid just stopped working which meant it wouldn't shut off the C02.
I believe the valve got stuck and you wouldn't hear that clicking sound when it opens the valve.
I was mad and took it back to my LFS and he gave me a new one, it's been running for 1/2 a year with zero problems.
Very accurate bubble counter, once you set it you can walk away and let it be. It's very sensitive though, so you will have to play with the needle wheel.
MG