Just bought a Canon FD 85mm f1.8, its got some specks of dust underneath the first lens on the mount end glass. Is it worth possibly trying to take it apart to clean?
On a lens of that length its likely you'd never see them in the image in the first place unless they're some seriously large specks. Camera optics are a tricky thing for a novice to mess with. You also need a completely dust free environment or you will most likely just make things worse. If you take it to a camera store they can do the job for you but it will cost about 100$ and I just saw this same lens for sale in the marketplace for 120. If you don't see spots, don't worry about it. I've rented Zeiss Glass from Panavision that even had a considerable amount of dust inside.