The safety device was activated on my Brother PE 770 because the thread got tangled down in the bobbin area. I've cleaned it out and now the top stitching is loose and is also sewing on underneath where the bobbin thread should be. It seems something got off when it got tangled and I cant seem to get it working right?

SOURCE: Brother 2001 sewing and embroidery machine.

The fact that your machine is turning hard says you still have some thread inside the machine that is binding up and activating the safety device. It must turn easily before it will work properly again.
Sometimes the machine must be disassembled to remove these threads.
sewman7

SOURCE: I have a Brother SE-270D

its the problem of the timing belt in your machine its extra loosen or extra tightned or is slightly came out of its position or finally broken.
as the machine is proper just missing the proper speed as it should be .
it is running continuosly as you stated.
check the timing belt and make it proper if its worn out and needs replacement this is how its done

There is an adjusting screw on the right side of the machine head. Follow the motor bracket to the machine head and loosen that big old screw or bolt which will raise or lower the motor giving you slack to remove or replace the belt.

feel free for further queries
thanks

SOURCE: My brother PE-400 sewing quit sewing

The "race" on your machine needs adjusting. Remove the bobbin cover, bobbin, & case. What you have left is the race, it moves when you turn the large wheel on the top right of machine. The needle also moves up and down. There is a hook on the race that catches the needle thread. Try moving the race to the line up with the needle. It may take a couple of trys but it should do the trick. Also clean any threads that may be caught on or arround the race. Hope this helps!

SOURCE: My brother LS-1520 sewing machine is having major tension problem

Try some metal bobbins, #15 or SA 156. that seems to help. If, you don't have a manual go to brother.com and download one for free

SOURCE: I have a Brother CS-770.

Hi. It's very likely that the needle is inserted wrong. Take the needle out and make sure that the flat shank of the needle is facing away from you (to the rear of the machine).

Try this and let me know if it helps, ok?

Robbie