having a fixed length and diameter smaller than the inner diameter of the torque tube 312 is provided the distal end of the tension tube 318 is securely attached to the stylet guide 6 and the proximal end 320 is secured to the adjuster block 322 for example by an adhesive the axial position of the adjuster block 322 can be adjusted to ensure the stylets 8 are initially positioned just inside the outlet ports in the stylet guide 6 torque coupler 314 is mounted on the coupler block 324 twist control knob stop pin 326 extends into a grove not shown and limits rotation of the control knob 316 fig1 is a detailed view u201c a u201d of the distal end tension tube connections of the tension tube shown in fig1 the tension tube 318 is securely connected to the proximal end 328 of the stylet guide 6 for example by a length of shrink tubing 330 fig1 is an exploded view of the sleeve and electrode slide block assembly of the embodiment shown in fig1 the right sleeve slide block 292 has a projection 332 which extends inward under the right electrode slide block 284 right sleeve connector 334 is mounted to the inner end of the projection 332 secured to the end of the proximal end of the sleeve 336 right electrode connector 338 is attached to an inner surface of the electrode slide block 284 and is secured to the proximal end of electrode.