The best place to have your brakes replaced at would be Midas they would be able to replace both your brake shoes and even brake calibers if they need replaced.
Rear brake cylinders or calibers are corroded and need to be replaced. Also drain the replace all brake fluid.
If you change the brake fluid every 50,000 miles the calibers will last the life of the vehicle.
Corroded calibers that are rusting and sticking. Moisture is in the brake fluid. Replace the calibers and replace all the brake fluid. It can also be a sticking slide pin on the brake assembly. Check that before replacing the caliber.
If u are talking brake rotors remove the calibers and the calibers support the rotor should almost fall off in your hand
Calibers are sticking. You will need to replace the calibers that are sticking and flush all the old brake fluid out of the system then replace it with fresh fluid.
On the front calibers they should move in when compressed, the back ones have to be screwed in.
Brake calibers can be rebuilt, but my advice is to just replace it with a new one. Be aware that if one is sticking then more than likely your brake fluid has become contaminate with moisture. I would replace both calibers and not just one. Remove all the old brake fluid and install fresh fluid from an unopened can.
When Brake Rotors Are To Thin To Turn On A Brake Lathe To Have The Minumn Thickness. They Need To Be Replaced.
You need to polish the rotors twice per month.
Sticking brake calipers. This can be caused by moisture in the brake fluid which will cause the calipers to rust. Replace the calibers and replace all the brake fluid. It can also be caused by driving with your foot on the brake.
It has probably rusted inside from moisture contamination. Do you change your brake fluid at least every 50,000 miles? Brake fluid attracts moisture and moisture destroys calibers. Replace the caliber and change your brake fluid.