allowed in the proximal electrode shaft portion 176 in one variation the motor drive unit can be adapted to over rotate the electrode shaft portion 176 at its proximal end by a selected amount which can be from 10 u00b0 radial motion to 90 u00b0 radial motion to compensate for twisting of the electrode shaft portion to insure that electrode portion 149 sweeps entirely across the surface of window 144 in general the window 144 in housing 140 can be configured to have a radial arc relative to the electrode shaft 176 ranging between 30 u00b0 and 180 u00b0 in one variation of housing 140 u2032 shown in fig6 it can be seen that the electrode portion 149 has a range of motion that extends across the radial dimension of the window 144 to ensure that any tissue captured in the window is resected as the electrode portion 149 passes the window edges 182 a and 182 b to function like a shear or in a scissor like manner the electrode portion 149 moves over ledges 186 a and 186 b on either side of the housing 140 u2032 and can bump into surfaces 190 a and 190 b by bumping into the surfaces 190 a and 190 b any over rotation in the electrode shaft 176 to accommodate twisting as described above can limit the rotation of.