Can anyone recommend a good replacement for the speaker in this model? Mine is damaged and I am having trouble figuring out which size I need. The cone measures a little over 5 inches and the mounting holes are about 6 inches from opposite corners. Do I need a speaker labeled as a 5 inch? Just how do I match this up? I just bought a 6 inch speaker and it is too big.

See if you can match it to one of the standard sizes at the end of this pdf file from Quam. This isn't every size ever made, but it's got a lot of them.

Can anyone recommend a good replacement for the speaker in this model? Mine is damaged and I am having trouble figuring out which size I need. The cone measures a little over 5 inches and the mounting holes are about 6 inches from opposite corners. Do I need a speaker labeled as a 5 inch? Just how do I match this up? I just bought a 6 inch speaker and it is too big.

IIRC, they were refered to as a 5 1/4 inch speaker. I think a 4" speaker might fit. The mounting holes should line up. Use it for now, until you find the right one.

It's probably a 5 1/4" "pincushion" frame. Rat Shack used to carry these. You might want to see if yours still has some kicking around.