A couple of weeks ago I purchased a Pro-30 scanner from a retired amateur radio operator. On the outside it looks mint, not a scratch or a bit of dust anywhere. I tried it out before I paid for it. It powers up with 6 AA batteries. I punched in the frequency for our local weather channel & it receives very well. When I turned it off and turned it back on the frequency (162.550 mhz) had disappeared. I know these radios have 3 button cells to keep your info when the scanner is turned off. The seller suggested that the batteries were dead. It took me forever to find 389/390 batteries locally but yesterday a bought a couple of packages at a jewelry store.
I opened to battery compartment and removed the old cells. Under them there was a green corrosion on the contacts which I cleaned up. I put in the 3 new 389 batteries, fired up the radio and entered 6 frequencies and let it scan. Everything performed as expected. When I turned the Pro-30 off & turned it back on the frequencies were all gone (all zeroes). I thought it put the button cells in the wrong way so I flipped them around. The radio still wouldn’t retain the memory. My old Pro-30 retains the memory even if you take the batteries out. I’m not sure what could be wrong. I’ve seen this happen out Radio Shack desktop scanners before but never got that problem solved either. Anyone ever experience this before & get it resolved?
I opened to battery compartment and removed the old cells. Under them there was a green corrosion on the contacts which I cleaned up. I put in the 3 new 389 batteries, fired up the radio and entered 6 frequencies and let it scan. Everything performed as expected. When I turned the Pro-30 off & turned it back on the frequencies were all gone (all zeroes). I thought it put the button cells in the wrong way so I flipped them around. The radio still wouldn’t retain the memory. My old Pro-30 retains the memory even if you take the batteries out. I’m not sure what could be wrong. I’ve seen this happen out Radio Shack desktop scanners before but never got that problem solved either. Anyone ever experience this before & get it resolved?
I have taken care of corrosion quite a few times before. The key is to remove as much of the case/internals as possible without cutting wires (but I have cut before). Once the terminals are as isolated as possible (remember wires 'wick' anything liquid and if so, will also carry that corrosion with it), and use a water/baking soda mixture generally applied. Once down to about as bare a metal as you can, finish by a type of burnishing until shiny. You must have all the residue out of the area befroe closing up the device. Then, fresh batteries and check them dilligently (the radio you save may be your own). You never know when batteries leak (I know I have had em leak on me, and I check them a lot). Good luck, I hope you can save the hardware! 
