Whakaotihia te rerenga e whai ake nei: I te tau 1975, i whakakorea e te kāwanatanga Communist o Czechoslovakia te whakaaetanga a Duka ki te mahi hei tohunga. Mai i taua wā tae noa ki te
I hinga te kawanatanga i te tau 1989, i mahi a Duka hei kaihoahoa i te wheketere Škoda i Plzeň. I taua wa, i mahi huna ia i roto i te Order, a ka pootihia hei Vicar Provincial o te kawanatanga ka mahi mai i te 1975 tae noa ki te 1987. Mai i te 1976 ki te 1981, i whakaakona e ia te kaupapa ki nga seminarians i te Faculty Theological o Litoměřice. I te tau 1979, i whiwhi ia i tetahi raihana i roto i te kaupapa atua i te Teological Faculty o St. John the Baptist i Warsaw, Poland.