Problems calibrating my Ph600 Milwaukee meter, won't go past 5.0

So I went to the hydro store to buy some 7.0 calibration solution to calibrate my Milwaulkee PH600 ph meter.

Placed it in the solution, let it sit for approx a minute, then turned it on.

Got a reading of 2.8 so I started to turn the screw to adjust up to 7.0

Problem is i could only get it to go up to 5 before the screw stopped turning.

I was told to let it sit overnight in the storage solution and see if I can calibrate it tomorrow.

Anyone else run into this problem? Anyone else have any solutions to this problem?

I am definitely going to get a new meter but in the mean time suggestions are greatly appreciated!

I have been through many ph pens.
I've been happy with the hanna i have had now for several years. I have 2 as I never trust just one incase it goes bad. PH pens should be cleaned after each use with a simple tooth brush and dishwashing soap like palmolive. I suggest you give your ph meter a nice scrub down and let it soak in the storage solution over night and give'er a try again. Good luck.

Did the meter dry out at some point? But yeah, what dirtyho said.

Update: I let the meter sit in solution over night and I cleaned the elctrode. Seams to be working fine, or at least I was able to calibrate it!

I did also buy another Ph600. I checked them against each other and they both seam to be working. This is good considering all my bagseed seedlings have been struggling due to me watering them with too high a Ph. My good genetics just broke ground and now I have two working ph meters so I won't be making this rookie mistake anymore!

Thanks guys I really appreciate the help. I won't ever have less then 2 meters on hand from now on.