[amsat-bb] G5500 Rotor Issue

I bought a used G5500 rotor that the previous owner had stored in a closet for several years and hooked up the power. The azimuth rotor is functioning as specified but the elevation side has a problem. When pressing either the up or down switches on the controller, I hear a hum from the rotor, indicating it is getting power, but nothing moves. Where should I start looking?

73 de W0HV, Jim in Raymore, MO (ex-N8AU)   Light travels faster than sound... This is why some people appear bright until you hear them speak.