My parking brake literally has no effect on my 1994 Volvo 850. I adjusted the bolt under the console as tight as it could with little improvement. I attempted to adjust the screws in each of the back wheels, but I cannot figure out what type of screwdriver to use. I removed the rear discs for easier access and there are 2 access holes. Which one do I use? When I shine a flashlight on them, its difficult to see anything. Please let me know if you can help me out.

Frank