Any body have any ideas of what might work and a good source for rare earth magnets strong enough to pull one of the balls out of the dirt?
I have a source for the magnets; they aren't cheap. I don't know how much force they would apply to a spherical object since only a little of the ball is really close (in contact) to the magnet. I will ask the source to do some testing and report.
However, I think you will need to run a tube in first to clear dirt from behind the shot or you won't be able to get the magnet close enough to exert enough force. In fact, maybe the technique should be the tube to find the shot and remove dirt, then the tube to refind and guide the magnet on a stick. Probably should use hard copper pipe so it dosen't alter the magnetic field too much. Maybe put a short steel tube on the magnet stick so there is an extension of the magnetic field, about one ball radius.