Hi this site is the annual accordion festival in MONtmagny quebechttp://accordeon.montmagny.com/carrefour/index
Foe builders there are more than these , but I know of
Marcel Messervier in Montmagny,
Reynald Ouelette (Mélodie), also of Montmagny and
Marcel Desgagné makes Sagné accordionms from up in the
SaguenayChicoutimi area