A portion of the Muon g-2 Storage Ring electric system, which provides vertical beam focusing, exhibited a special behavior that produced a characteristic evolution of the stored beam during Run-1 of the Muon g-2 Experiment at Fermilab (E989). A method to reconstruct the Run-1 electric guide fields has been developed, which is based on a numerical model of the muon storage ring and optimization algorithms. This method takes beam profile measurements from the Muon g-2 straw tracking and calorimeter detectors as input, and a full reconstruction of the time-dependent fields allows the reproduction of detailed beam tracking simulations altogether with ring lattice parameter calculations for acceptance studies and systematic error evaluations.