The Problem: Over a period of time, generator slip rings become tarnished, oxidized and coated with dirt and carbon. This contamination build-up results in poor contact between the brushes and the slip rings. The voltage regulator attempts to maintain a constant output voltage by supplying enough current to support the load. When the resistance is high due to dirty slip rings, the regulator must supply a higher voltage in order to obtain the same current. This causes the regulator to work harder, run hotter and fail prematurely. In addition, the increased resistance causes the slip rings to run hotter than normal, further aggravating the tarnish and oxidation problem. The brush material will also cause the brushes to stick in their holder and stop electrical flow to the rotor. The answer is to keep the slip rings clean.