In situ flywheel balancing

A system comprising:

• a flywheel including a rotatable mass component and one or more axles coupled with the rotatable mass component, the one or more axles extending from a top of the rotatable mass component and from a bottom of the rotatable mass component, the flywheel including a plurality of receptacles;
• a balancing slug that deforms when placed into one of the plurality of receptacles, the balancing slug including:
• a plurality of fingers located around a center channel in a substantially cylindrical body of the balancing slug, the plurality of fingers flexing relative to one another, the plurality of fingers being pressed toward a center axis of the balancing slug when the balancing slug is inserted into a receptacle of the plurality of receptacles, the center channel configured to receive a set screw that exerts a circumferential force on the plurality of fingers when the set screw is placed in the center channel;
• and
• the balancing slug includes a circumferential ridge that is constructed from a softer material than the receptacle of the flywheel, the circumferential ridge deforming when the balancing slug is installed in the receptacle of the plurality of receptacles;
• and
• an enclosure enclosing the flywheel, the enclosure including a balancing access port adjacent to at least one of the plurality of receptacles, the balancing access port allowing the balancing slug to be inserted through the balancing access port.