I have a pair of these, serial numbers 500 before you, in a dark gray finish. Solid, heavy, good sounding little things.
Coincidentally , they were in fantastic shape except for the missing fuse cap and fuse. I wound up getting a new fuse holder and am using 2A fuses, as found in a Google image search.
I would be curious to know what fuse rating you found in your speakers, if you could pass that along.
Thx!