Originally Posted by NapaJohn

It (likely if it's like mine) has a metal-cleated cotton motor belt as well as timing belt. Whenever you clean it or oil it be very very careful to not get any water or oil on that belt as it will cause the cotton part to fail more quickly. They have discontinued making the belts, so they are hard to come by. My belt has been replaced twice since it was new (once in the 1970s and once in the 1990s) and it is beginning to fail and I haven't found a replacement and I've taken it to three different sewing repair shops--have only seen some used ones on a UK site, but am wary of those.