The paper cone has completely detached from around the amature in this speaker. Otherwise, the paper is in excellent condition. I intend to glue it back and reinforce with fine paper. Any suggestions as this repair will likely make or break it for sure.

What I have done with paper cone speakers with a balanced armature (not electrodynamic speakers with a voice coil) ..is.....if the cone is really bad but all is there: I completely remove it ...cut the original seam completly so cone can be laid flat. ..Then.. If black in color I use from walmart..black tag board in the craft or school section...Using contact cement on back of original and on tag board ..I let dry till tacky and stick together..(ONLY ONE SHOT AT THIS) Hint: don't cut tag bord leave in large sheet and "draw" a circle with contact cement..After drying..then cut around original.. I reform back into cone shape and glue strip along seam to hold together... If brown in color u can use a grocery bag or tan tag board or a vanilla file folder works good... I have had cones that were tore in 10-15 parts and glued to tag board and have had good success...

:What I have done with paper cone speakers with a balanced armature (not electrodynamic speakers with a voice coil) ..is.....if the cone is really bad but all is there: I completely remove it ...cut the original seam completly so cone can be laid flat. ..Then.. If black in color I use from walmart..black tag board in the craft or school section...Using contact cement on back of original and on tag board ..I let dry till tacky and stick together..(ONLY ONE SHOT AT THIS) Hint: don't cut tag bord leave in large sheet and "draw" a circle with contact cement..After drying..then cut around original.. I reform back into cone shape and glue strip along seam to hold together... If brown in color u can use a grocery bag or tan tag board or a vanilla file folder works good... I have had cones that were tore in 10-15 parts and glued to tag board and have had good success...
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I have used Elmers Glue with great success. I make sure the two halves of the torn cone are somewhat mated and then spread the glue in a thin layer on top of the break.

It works very well.

Thanks
Lou