All metal detectors break down… And every detectorist tries to solve these problems in his own way. Some individuals may surprise you. See: here’s hellish bottom for Garrett ACE 150.
I understand that not many can make a shaft with their own hands (have you seen a self-made shaft which is better than the original?). But one does not simply slip the metal detector control box over the water pipe!
What would I have done in such a situation?
1) I would have tried to find a mono-crutch and slip the control box with a coil over it. The advantage of such a solution is that you have an armrest at once. And it is the one that can be the biggest challenge. Here is an example of how such crutch may be used instead of a shaft.
2) I would have found a straight stick (fishing rod, plastic pipe) and fitted a bicycle bar end to it as a handle. The example of such a shaft is here http://md-arena.com/samodelnaya-shtanga-luchshe-originalnoj/. As for the armrest, I would have made it of a plastic pipe cut in half.
Some latest news… MarsMD is making a universal shaft. Compatible with more than 50 different metal detectors!