Replacement knobs and reservoir parts are available for many adhesive dispensing systems. New knobs replace missing or broken pieces on case sealers, dispensing cells, and other control units. Reservoir parts replace or improve components to ensure reservoirs run efficiently at all times. Reservoirs regulate internal pressure and accommodate different volumes of adhesive. Individual pressure regulators, liners, and switches can be replaced. Pressure regulators are an integral part of every reservoir. Users can repair old or malfunctioning regulators, gauges, and valves with readily available replacement parts. Reservoir liners protect the internal components of regulators when adhesive is not being used. Safety start switches provide an optically-triggered start option in compatible dispensing systems.