Milwaukee CO2 needle valve starting to fail ?

[magnosis]

My pressurized co2 setup has been up and running for a while, it's been pretty good.

Yesterday I noticed the PH had dropped to 7.0 from it's usual 7.4-7.8 range.  The tank looked like it was filled with 7up.  Within seconds I realized my CO2 needle valve was letting co2 flow at a much accelerated rate.  I haven't touched it in weeks and so far its been reliable.

The regulator is set to 60psi.  I set it up this way from the get go because I found it was a lot easier to adjust the needle valve (and it was advised from fellow members).

Trying to re-adjust the needle valve yesterday was a pain.  Basically I can shut it down completely, then whether I give it 1 or 5 full turns, the out flow was the same.  It was near impossible to adjust to the usual 1.5-2.0 bubbles per seconds >.<

Is this something... normal with Milwaukee needle valves ?  I'm aware this isn't top quality equipment, but I would have hoped it'd be reliable for more than 2 years.

What do you think ?
Should I set the regulator to a higher pressure (100psi) to make it easier to adjust the needle valve ?  Or to the contrary do you think 60psi is too high and either a) makes adjustment more difficult than at lower pressure or b) high pressure puts too much stress on the needle valve and could have damaged it ?

Ugh. Not really in a situation where I can affort a high-end valve right now :-/