I was told by my parts supplier that there are two different belt sizes.
The groved side of the belt needs to contact the goves on the drive shaft. If your belt is smoking it sounds like something is not quite right with the belt or the drum or pulleys are not free to move. Make sure the drum is free to run before you bolt everything back together again.
See this page for the belt & pulley configuration (at least on the one I fixed)
http://homepage.ntlworld.com/pete.costello/pics/CredaPulleys.htm
Peter C
June 2004