recently my Nikon FE has develop a problem. The light meter needle shows the correct light for the largest aperture, but when I stop down it moves only reluctantly to reflect the new aperture. It is as if something partially blocks it, perhaps dirt. There is actually a faint sound as the needle moves.

If I keep the camera on the largest aperture the camera effortlessly shows the correct value. The problem only arises when I change the f-stop.

Can I fix this myself, or should I get it to the repairman?

thanks for any suggestions