Theory A: These relays do not withstand vibration well. When closed, the points bounce open and when open, they bounce closed. The resulting arcing causes the points to pit and burn. Theory B: With no arc suppression across the V23073's coil, the energy stored in its magnetic field dissipates by arcing across the contacts when the relay is de-energized. The resistor across the coil in the MGR series relays absorbs the energy and protects the contacts and other circuits connected to the contacts. In addition, the MGR series relays have been tested over the full range of vibration frequencies equivalent to the range of RPMs involved without contact bounce.