See if you can un-mount the magnets and recharge them. Before doing that figure out what direction the poles are. If you have a compass aim it at the pickup poles (reassembled) and see what direction it is.

I am not familiar with the construction of that pickup but I am guessing that there are two magnets under each coil just like a P90 guitar pickup.

Do you know if they are ceramic or Alnico magnets? If they are ceramic it will much more difficult to recharge them without the proper equipment. Most likely they are Alnico.