A first aspect of the disclosure concerns a driving assembly for a power toothbrush which includes a drive member, specifically an E-core electromagnet, a driven member which is responsive to the action of the drive member and a workpiece mounted on the distal end of the driven member. The drive assembly includes an interface registration member, to one end surface portion of which is secured the end face of E-core electromagnet, another portion of which is configured to produce a selected registration of the driven member and the driving assembly, and still another portion of which is configured to produce a selected registration of the interface member relative to the handle of the toothbrush.A second aspect of the disclosure concerns a split bobbin assembly for an electrical coil portion of an electromagnet in a power toothbrush. The split bobbin assembly includes a first portion which mates with a portion of the appliance which is exposed to the operating environment of the appliance and is made from a material which has sufficient chemical-resistant properties for tolerance of exposure to the environment. A second portion of the split bobbin is made from a material which is resistant to heat so as to withstand soldering of the electrical coil wires to the terminal pins positioned in a base part of the bobbin assembly. Connecting elements on the first and second portions join the two portions together.