How do you perform Kerfed Lining reglue

[Matt Haugen]

I just found an old yamaha red label 12 string and the kerfed lining has broken off from the top of the guitar throughout the entire lower bout. My question is how do you apply pressure to reglue the lining. My only access is through the sound hole. Thank you.

[Antonio Cotichini]

You should try to make some sticks, in the proper length to point from one side to the other and from the top to the back (obviously inside the box!) after applying the glue. It's the only solution I would go for. It's boring to do but works.
Good luck
Antonio