I've bought a few homes to turn into rentals and had to find septic and below grade wells. I run a fish snake for installing electric inside the pipe. It will stop at the 90* elbow at the well, and put a piece of tape on it. Now at least you know how far from the end of pipe inside to well it is. Mark a radius line outside from where you know it exits the building. Should be somewhere close to that arched line.
Now try divining rods. I believe the magnetic poles of the earth cause the water in your body to magnetically effect steel rods. Think about it. We conduct electricity, and magnetic lines of force are always cutting through your body at different angles from the magnetic poles. Electric is generated by magnetic lines of force going through a rotating coil in a generator from permanent magnets or an alternator with electromagnets. That moves the electrons in the copper wire coils, just like I believe it could move the electrons in our body. Very weak lines of force, but the rods seem to move like you are the magnet. Don't know if it's a disruption, or something making it stronger, but it works. A friend of mine with a septic pumping business has a set he uses to find septic lids all the time.
Around here the top may be down 4 feet deep, so driving rods in the ground are no where near deep enough. How would you know if it were a rock, or you were driving it through the cap ? Many are aluminum ! Puncture the suction line with a pin hole amount of damage in a two line shallow system, and you're fixing another problem. I certainly wouldn't poke around the ground in the vicinity of water lines. I also wouldn't say there is any reason for a well to be a certain footage from the home. Many are just off the road where the well drilling truck could back in and be far from the home. My own and one rental is about 50 feet from the home.
When I find it, I drill the casing side and install a pitless adapter, install submersible pump, and extend the casing above ground with a Fernco coupler and 6 inch PVC to be able to put a T pipe into the adapter to pull the pump.