Got this old bike with a side pull back brake and I had to put some new shoes in it. Now it drags all the time on the side where the cable is (the right side of the bike as seen from the back).

I've fiddled with the adjustment a few times and have oiled the centre parts but I can't fix it.

Thought it would be so easy.

What am I doing wrong or not doing that I should? Can anyone help?