The fuse is located immediately behind the male plug connector at the back of the unit when looking at it from the rear. It’s a black cylindrical fuse container about 1-1/4 inches tall and attached to the metal chassis.
You’ll have to remove the unit from the wooden case. Turn it upside down with the rear facing you. Place the unit on a soft surface while upside down so you don’t damage the reel or recording assembly. The fuse will be on the right side behind the plug.
You’ll need to remove the black fuse holder by unscrewing the nut that holds it to the chassis. Once you remove it, the fuse will easily come out of it.