rotated to cause the mounting cup 20 to rotate but when a certain resistance is reached for example indicating that the spiral needle 24 has rotated all the way into the tissue the attachment nipple 104 is caused to slip within the slot 56 so that the mounting cup and needle aren 39 t forced to continue rotating and otherwise cause injury to tissue in which the needle is inserted also the attachment nipple 104 will pull out of the slot 56 if more than a certain resistance is reached when pulling the drive shaft 4 away from the mounting cup 20 the handle 8 of the drive shaft 4 includes an enlarged rear section 8a in which is formed a slot 120 the purpose of which is to receive and hold the circuit carrier 28 the slot 120 simply serves as a holder for temporarily receiving the carrier circuit 28 while using the probe to thereby keep the circuit carrier from getting entangled or otherwise in the way to hold the circuit carrier 28 in the slot 120 a keeper 122 is molded integrally with the handle 8 the keeper 122 includes an integrally molded living hinge 124 and a snap in cover 126 which snaps into a slot 128.