There may be a ridge created by wear at the inside edge of the drum catching on the brake shoes. They can be a bear to get free. I have gotten them loose by removing the axle shaft and outer bearing which enables more movement to get the brake shoe past the ridge. Ugly and heavy work, eat you Wheaties before jumping into this.

Last edited by Paul_WNC; 05/25/2014 5:15 PM. Reason: spelling

1941 Chevy 1 1/2-ton WW2 4x4 dump truck
In the Stovebolt Gallery
Lots more pictures