BROKEN CLUTCH PLATE BOLT ??

[95ProbeGT]

hi, i ran into a problem. as i was installing my new clutch, i was tightening the 6 bolts with the springs on the pressure plate. i had tightnened them first with a screwdriver until i couldnt turn anymore. them i used my 3/8 torque wrench which was set at 7.5 foot pounds, as listed in the instructions, but i still broke a bolt off, half way in the threads. it seems when i use the torque wrench, the bolts dont seem to finally stop turning, they just keep turning and dont grab so the wrench doesnt click at the specified torque setting. has anyone had this problem also. how i can make sure that the pressure plate bolts are tight , without using the torque wrench? i dont want to break another bolt off or strip a thread. thanks!