I'm one of the unfortunate ones that received a damaged GY41. I ordered some guitar clamps, glue, 2 sided tape, magnets, and a small piece of spruce. I got the two broken halves aligned as best I could, applied the glue and clamps. 24 hours later I enlisted my wife with her small and skinny arms to help place small strips of spruce which I had cut and stained, inside the guitar at the break line to add additional strength. Even with small arms, this was the most difficult part. And once her arm was in the sound hole we were flying blind. She did pretty good and only messed up one overlapping one we had already placed and glued. I used the trick I saw in YouTube to place a piece of the tape on a small 1.5 round magenet, affix the small wood strip to the magnet, apply glue to the wood strip and place where you want (or at least try by feeling). Then place a similar magnet to the outside holding the strip in place while it drys. We did this over the course of about 3 days.
The repair seems very strong. But when finished the break line was still rough so with great apprehension I taped off only exposing about 1/4 to each side of the break line and sanded the line smooth. Started with 600, then 800, 1000, 1200 and finally 1500. I've restored cars so had this sand paper in the shop. And finally I used rubbing compound, then polishing compound and you can see the result. It's still visible but smooth and blended so I am happy with the result. The guitar plays and sounds great, definitely different than the GF45 I replaced it with. I need to give the 41 more play time but at this point I'm loving the 45 a bit more.
It's scarred for life but was worth the $60 or so to get it to a playable piece.