Unklebuck

The bellows you show are gear driven. There is no belt. You should be able to take it apart using regular penetrating oil. WD-40 is not a penetrating oil. If the hand crank turns easily, you don't need to take it apart. If you do, use high-temp wheel bearing grease to pack the gears. There is an oil hole in the casting to oil the crank from outside. There's no need for a seal, however, if you want to use something, use high-temp sealant without a gasket.