Well in the olden times when you had a brake job done on your car the mechanic would clean up the brake drums and the term used they would ARC the brake shoes by sanding off the high spots in the shoe material. The lining in those days were made of asbestos bearing material and and is very harmful to your health.
So you may have brake shoes that don't make good contact with the brake drum.
Yes I am old and I did my share of brake jobs and clutches but I am still here LOL
Steve