Complex sentence: From 1988 until 1992 he was general manager at FC Schalke 04, on the same position he worked from 1992 until 1995 at Hamburg and from 1998 until 2001 at Arminia Bielefeld.
Split into simpler sentences: From 1988 until 1992 he was general manager at FC Schalke 04. From 1992 until 1995 he worked in the same position for Hamburg and from 1998 until 2001 for Arminia Bielefeld.