I was disassembling the rear brake hub on my 1978 Bianchi Snark to check to see how much brake pad I had left for my brake was not grabbing the wheel in order to stop it. Well the break pad was just fine but still I put it back together and the breaks still refused to grab the wheel in order to stop the bike. So, I took it apart again and sanded the pad to roughen it up and I wiped the drum to make sure there was no oil present. Still the brake refused to grab. Anymore suggestions for my problem?