Let it soak for 24 hours or so then try again. Once you pre-soak the electrode you dont want them drying out. resoaking the electrode may fix the problem.
Its no gaurentee but it may work. I`ve read of a few other people doing that and it worked for them but they were using a Hanna PH tester. I have a Bluelab Combo Meter and the replacement probe is $70.00.
You know, if you were gardening organically, you wouldn't be dealing with these issues. I haven't even used my pH pen since I made the switch. If done correctly, the whole system is self regulating. All you gotta' do is water! wak