brake linings

[Al 29Tudor]

Need some sage advice,
We have adjusted the brakes, all the linkage is moving freely, taken all the slack out of the clevis ends/rods, new cast iron drums, rebuilt the tracks, almost all parts have been replaced, sanded the shoes and there is very little braking when the brakes are applied.
Has anyone ever experienced shoes that become ineffective? or too hard to work any longer?
What are we missing?



















Thank you for any advice you can offer.
Al