Without pictures or detailed info, I would say that you could just use and PAS sensor with any controller. PAS sensors are pretty basic and standard pieces, it only costs a few dollars for a new one. PAS sensors basically just get a pulse from a magnet to know that you are peddling.
Not all PAS sensors work the same, though all the common ones use hall effect sensors in them. Some have one and some have two hall sensors. The output is mostly the same - a signal that pulses 5v when the pedals are turned. Some are handed and all are directional, so the direction that you pass the magnet and the orientation of the magnet is important.
If you mount the magnet disk the wrong way up, it won't work when you pedal forwards, nor will it work by pedalling backwards with it mounted the right way up. The handed ones won't work when you fit it to the wrong side of the bike. There's 4 combinations of magnet disk orientation and rotation direction. If they're handed, only one works. If they're not handed, two will work.