Drive Belt on Pioneer PL120-II Turntable

Somewhere throughout the years I've inherited a Pioneer PL120-II turntable. Recently I thought I'd get it working to use as a backup for my Technics SLD-2. The Pioneer wouldn't work due to a missing drive belt. I ordered one on-line and for the PL120-II it specified a 23 1/2" belt. When I went to replace it, the belt seems much too big. There is an active drive shaft around which the belt goes (I thought) and a passive idler spindle that the platter slips down onto. My thought now is that there's some kind of rubber pulley assembly that affixes to the drive shaft that I'm missing. (There's a sticky, melted-rubber-like substance all around the drive shaft.) Can anybody shed some light on this?