Avid Juicy problem
I've got a set of Avid Juicy 5's that are 2 years old. The front brake is working fine, but the rear brake pads are catching the rotor quite a bit, like only spining 2 revolutions before stopping. After I ride it for a while, it loosens off and the wheel spins relatively freely. I hardly even have to move the brake lever for the brakes to engage either, and I think this is getting worse.
From these symptoms, does it sound like they need to be bleed? They are getting a bit rusty and well used, so if it may be something more major, I might just shell out and upgrade to a new set.
Try to push the pistons back into their bores. Use a slotted screwdriver between the pads and rock them back and forth until the piston edge is flush with the bore. If the pistons cannot go all the way back in, the system is overfilled. Reposition the lever parallel to the ground, then open the bleed port at the lever and reset the pistons. This will push excess fluid out of the system. Close the bleed port and clean up the fluid.
After the pistons have been reset, center the caliper. You do this by loosening the bolts that attach the caliper to the adapter so that the caliper can "float" and the cps washers can move. Make sure the CPS washers are clean and pit-free. I like to use a light film of grease on those washers. Squeeze the lever, and while holding the lever, tighten those bolts back up nice and evenly. Make sure that the torque does not displace the caliper. Check to make sure that the space between the pads and rotor on each side are even. Make sure the pads are hitting the rotor nice and square.
You may want to make sure that the pads are okay. Also clean around the pistons (in the caliper) with alcohol. If you pump the pistons out, and one seems to stick, you clean it, use DOT fluid to lube it up, and then pump it in and out. Repeat until it moves more freely. All this is basic maintenance. If you don't feel comfortable doing any of this, bring it to a shop.
If the lever feels spongey, you have air in the system and it requires a bleed.
I do not believe that any of that warrants a new brakeset.