From the introduction to “Minhagei Lita”:
“During the fifty years after publication of the Mishnah Berurah until the destruction of Lithuanian Jewery, communities did not adopt those decisions and reccomendations of the Mishnah Berurah that ran counter to the traditionally accepted minhagim. Not even in Radin, where the Chafetz Chaim had his Yeshivah, did the community change the traditional customs in favor of those urged by the Chafetz Chaim. Hence, many people today mistakenly assume that whatever the Mishnah Berurah recommended must have been the accepted custom in Lithuania.”