Did you triple check the belt part number is correct?  There are a couple different widths of belt.  Any chance you got the wrong one?  On the lower sheave gap I know mine is wider than the 3/16" spec but it has been for years.  I use a straight edge and try to align the top and bottom sheave as close as I can with the adjusting bolts.  It's a real poor design.  It sounds to me like something is binding in the lower sheaves.  Doesn't take long to take back apart and double check.