brown "gummed" tape.. the type you lick and stick
Can be removed with moisture when needed.

The other tape would be used by luthiers/ guitar builders etc to stick on the binding when placing it in the groove.

Need some.. I'll send you some.

The gummed stuff nearly any one who ships has this or go to Staples and get a small roll in a dispenser.... cut it to size.. wet it... good to go.

Another thought is pre gummed cloth bicycle handle bar tape.. bike shops always have cut off surplus pieces

Thanks. Isn't the bike tape slightly padded?

I'll try the shipping tape first. I'm glad I took the box apart to check it out. I told the owner I fixed two things on the box while I was looking at it.

She wondered if she could just rotate all of her boxes through me, so I can gradually get them all in good repair.

Cloth bicycle tape is not padded.

Inside my GGFs 1880 2 1/2 row D/G is a section of a playing card .. cut to a strip about 1" wide and creased then glued over the worn/torn fold... very cool.

Gaffers tape might be a good choice. It is quite strong, like duct tape, but it doesn't leave a gunky mess like duct tape does if you try to remove it.

I have used gaffers tape for internal attaching and sealing of different things.