Hello EMan,
Ive not been on the forum for a long time but saw Joe Rossis name and just had to investigate. Joe (pronounced Joey) lost his third finger as a result of a gunshot wound during WW2, although he was lucky enough to be possessed of large hands. I believe he had the stump of his third finger surgically removed so that he could play again, and what a great job he made of it. He mainly played with his three surviving fingers, but also made quite prolific use of his thumb. His little finger was about the size of my forefinger, and it seems he learned to use it like his missing third finger.
Mazurka Fantaisie requires four note legato runs in the first two bars, and most of the older French players used fingers 1 to 4 to achieve that. Some of the more complicated musette pieces required almost equal strength in all fingers, and was beyond even some of the big name players, who only made occasional use of the little finger. Most old school French musette players were able to play nearly all of the standard pieces using three rows only with the inner 4th row of buttons being used as a cheat, mainly for chords and arpeggios. Most of them learned to play as children and developed techniques to pass their fingers over and under each other when playing at speed. Very few of them played to any particular system after they became professional. One of the most successful French recording accordionists was Aimable, who wasnt a very great technical player at all, but he developed his own style of fingering and bellows control that gave him a unique sound.
Joe Rossi played the same style as the teachers Andre Astier and Joss Baselli, who wrote a teaching method together, which unusually for French accordion methods, allowed use of the thumb, but only on the outside first row. I would imagine that having a missing third or fourth finger was not so much of a disadvantage to French schooled chromatic players as it would be to a PA player. The composer of Mazurka Fantaisie was Medard Ferrero, who also wrote various method books, and forbade his students to use their thumbs on the basis that anybody who did, would not play so well. Most of the musette pieces written in his day were composed to be played without use of the thumb and only occasional use of the 4th row. Very few French accordions had/have 5 rows, and most French players, even today, have no use for a 5th row. Of my 4 instruments, only one has a 5th row, and it serves no purpose at all, other than to make the accordion heavier than it needs to be.
Joe Rossi very seldom played any tunes straight. He had a tendency to prefer classical music, which he also played with considerable embellishment. It was as though he was always trying to compensate for his missing finger. Although he was possessed of considerable ability, he never seemed to have a big following, probably on account of the fact that he tended to shy away from the popular dance numbers in favour of what I would call demonstration pieces, composed or adapted to show off the skill of the player.
If you Google partition mazurka fantaisie youll get the first page of the piece as a photo on the web page. Partition is the French word for score. The full score can be had from various websites, usually for a few Euro, plus postage, but be very careful of the free offers, as you will be prompted to download other programs which could contain dodgy material. Im sure it is listed in the Paul Beuscher 110 Succes Musette series, probably volume 1, but that is a large pricey book that would only be worth buying if you were into learning a lot of musette tunes.
As a consolation, here is a link to the tune being played by Medard Ferrero, the guy who wrote it.
http://www.musicme.com/Medard-Ferrero/videos/Mazurka-Fantaisie-44737841446E724364466F.html
I studied using his method without the thumb. However, I never started to play until I was about 30, and consequently never progressed beyond about an intermediate stage. Its a sad fact that the accordion seems to be losing popularity, even in countries like France where it often featured in the pop charts.
