In a defense of the title on June 18, 1926, Stein also took the VDF German National Flyweight Championship in a tenth-round knockout of Schmidt at the Radrennbahn in Treptow, Germany.

[2] Facing one of his most competitive opponents, Stein lost to 1931 Canadian World Bantamweight Champion, Norwegian-American Pete Sanstol on July 13, 1926, in a fourth-round newspaper decision at Luna Park in Halansee, Germany.

[2] Stein fought a German featherweight championship bout on March 1, 1928, against Eric Kohler losing in a fourth round disqualification at Ausstellungshalle, in Dresden.

[4] Stein fought primarily in Paris, and Belgium, between May and December 1929, meeting quality opponents but no world champions, where he established an impressive record of 12 wins and 3 losses.

[4] He met the incomparable reigning World Flyweight champion, Italian-American Frankie Genaro in an eighth round no decision bout on February 26, 1930, at the Sportpalast, in Schoeneberg, Germany, which he won by disqualification.

[4] On April 22, 1932, in one of his most important victories, Stein won the VDF National German Featherweight Championship in a fifth-round technical knockout against Paul Noack in Spichernsaele, Germany.

[4] Only months after relinquishing the German Featherweight Title, Stein was forced to flee Germany for Prague, Poland, to escape Nazi persecution in 1933, where he continued to box at least through 1937.

He fought at Prague's Lucerna Hall through 1934, but the frequency of his bouts, the quality of his competition, and his percentage of wins diminished after he was forced to flee Germany, possibly because of advancing age, his need to find other work, or because he had less time or resources to train.