I have seen leak detectors at work before, alot of the "tools" they use are pretty amazing, like tinfoil hat amazing in my opinion. I have seen them come close, and get lucky, but never super sure of themselves and absolutely never a guarantee beyond what you could figure out without them.

I have found that if you have a pipe full of water, and plug both ends with econoplugs or bladder plugs, and introduce compressed air slowly into the line, if you use a stethoscope and listen to the concrete, the combination of the air and water going through the leak makes alot more noise and is easier to locate. We have found some leaks under floors in waterlines like this before.

How long of a run is it to just trench a new line in from the jet to the pump? You could go straight out of the concrete into the grass or yard and then over to the pump and back in again. Basically reroute it so it does not require alot of sawcutting. Good luck, hope everything works out for you.