Rubuta ci gaba don wannan sakin layi - A shekara ta 1975, gwamnatin Kwaminisanci ta Czechoslovakia ta soke izinin Duka na yin aiki a matsayin firist. Tun daga lokacin har zuwa lokacin da mulkin ya rushe
a cikin 1989, Duka ya yi aiki a matsayin mai zane a masana'antar Škoda a Plzeň. A halin yanzu, ya yi aiki a asirce a cikin Dokar kuma an zabe shi Vicar Provincial na lardin kuma ya yi aiki daga 1975 zuwa 1987. Daga 1976 zuwa 1981, ya koyar da ilimin tauhidi ga malamai a Kwalejin Ilimin tauhidi na Litoměřice. A cikin 1979, ya sami lasisi a cikin ilimin tauhidi a Kwalejin ilimin tauhidi na St. John Baptist a Warsaw, Poland.