and a second groove 98 on the second end 62 of the contact arm 56 the second end 94 of the first torsion spring 86 may engage with groove 96 of the contact arm 56 and the second end 94 of the second torsion spring 88 may engage with the groove 98 of the contact arm 56 the engagement between the torsion springs and the grooves may include a straight portion 100 of the second end 94 lying flush with a surface of the grooves 96 98 alternatively the second end 94 may hook onto or otherwise engage with the grooves 96 98 thus a rotor assembly 50 has been described that is capable of u201c top down u201d assembly a procedure that is capable of top down assembly will show a reduction in assembly time of a product and may also be manufactured using an automated system fig4 u2013 9 demonstrate how the rotor assembly 50 may be assembled using such a top down assembly process fig4 shows the first rotor half 52 positioned such that protrusion 78 extends outwardly and recess 84 is made available fig5 shows the first torsion spring 86 inserted within the recess 84 such that the first end 90.