Sluggish pH meter

[Delphinus]

My pH meter has been verry slow to give a steady reading as of late. I wonder if it's my probe or maybe just a sign of a low battery?

For example say my tank is 8.3 ... I turn the meter on, and it will read 7.3. It will then increase in increments of 0.01 for the next few minutes until eventually it settles in at 8.3. It honestly takes about 3 minutes or so to get to that reading.

Thinking the probe was dirty I cleaned it, then soaked it in vinegar, then recalibrated. That wasn't it -- still sluggish.

What do you figure ... bad probe, or bad battery?

(I will try replacing the battery tomorrow, but fishing for ideas in the meantime.)