sand paper/ragmal/should be used on both the hub inner face and the brake shoe,,
and also only rubing surface wont solve the issue,, u also need to wound a witre around the pivot about which the brake sshows are held,, so that they casn make a good contact with surface when opened..
infact when brake shoes are totally faragh they even after full braking dont make gopod comntact..
the boy who did it was a new in city,,he said here people are very gulliable,,,and my master says to jut swp items,, i was amazed how good its working npow,,