Ph Meter problem - Calibration

I purchased a Pinpoint Ph Meter on CraigsList. It has a Hanna probe. The guy I bought it from had it in his sump, and it was reading in the low 7's. Empty tank, no fish, no coral. Took it home and put it in my sump. 7.11 reading. Steady. I bought some Pinpoint calibration fluid online (7 and 10), and attempted to calibrate. Did 7 first, was a little low, so I adjusted up to 7.01. I then rinsed the probe, and tried the 10 fluid. Got a reading of 7.49. Turned the adjustment screw and got it up to 7.64. It would not raise past that. So I thought it may be a bad fluid. So I tried a 10 fluid I got at an LFS (different brand). Same 7.64 reading.

So my question is, bad probe or bad meter? I will buy another probe if need be, but don't want to waste the money if the meter is bad.

Anyone have any idea?

 

I would assume it's the probe. That's the item that needs to be periodically replace.