After dunking in freshwater for the 5th time, my gimbal was also extremely erratic, with no control over it. I took the plate off (the one with the three screws) and sprayed the pot with tuner spray (DeoxIT to be exact) since it brought my gimbal back to life after the last submersion. It didn't work this time. I decided to put the Phantom back in my boiler room, which is a great hot/dry place to dry out electronics, and amazingly the gimbal came back to life the following day. Now all is well.
So if you can't get help from following the thread mentioned in an earlier post, you might want to try the tuner spray. Anything is worth trying, rather than plucking down big $$$ for that new camera/gimal.