The Mauna Loa is made out of nissa wood which was not used by any other company than Lyon and Healy as far as I know.You should resist your initial inclination to replace the wooden tuning pegs because they belong on these models and work fine when you get used to them.Two ukuleles from the 1920's: The one on top is a plywood Harmony uke and the one on the bottom is a Mauna Loa, an inexpensive line made by Lyon and Healy.Both of these have wooden tuning pegs which mostly were not used after the late twenties.Over many years, Chuck assembled his own world-class collection of vintage Hawaiian and Mainland ukes, including some amazing one-of-a-kind pieces. Jumpin Jim2015 Chuck, I got the Kamaka concert (2004) you suggested 10 years ago and much later a Martin. They keep me amused during the dullness of the working day. His post-fire ukuleles are unique (unusual) designs often with an oval sound hole, whereas those made before the fire are more traditional and characterized by a wave-shaped head stock.
I don't know how Peter distinguished between the decades in terms of the serial numbers.
These serial number apply to all Martin guitars, flat top and arch top.
It does not apply to ukes (except for the first year, they do not have a serial number).
These and similar forms are still popular throughout Latin America, Spain and Portugal.
These and other European instruments were originally imported into Hawaii by the immigrants, and continued to be imported through the late 19th century, even after local makers started building their own.