Mystery Bamboo Flute!

This flute belongs to a friend of mine, who mostly does percussiony stuff for oldtime/bluegrass music, and has never been able to play it, so has loaned it to me. She got it from Grey Larsen 20+ years ago. It’s in the key of A. The first octave is great but the second one is not in tune. Could that happen if it’s been sitting unplayed for so long? It could use some TLC. Guesses as to the maker? She thought Grey Larsen might have made it but wasn’t sure. The makers mark is below. Ideas about TLC as well?

Mystery Flute

Makers Mark