9 hours for Carolina's is perfectly normal. I have had males stay on for like 12 hours! and sometimes they just wouldn't get off, lol.
I have found male Carolinas to be very stubborn on dismounting. One trick you can do to encourage the male to dismount is to very gently grab him on the thorax with two fingers. And just hold him very lightly for a few moments, don't worry no harm comes to the male by doing this. But you just gently hold his thorax, don't lift up or anything just give slight pressure and he should begin dismounting. If he is still connected he should begin to disconnect his abdomen from the females. After 8 hours the male should be done transferring sperm so if he is still connected you can do this trick. I have done it a few times to particularly stubborn males and it has worked.
