A semicolon should precede the conjunctive adverb.
The conjunctive adverb is "however". It joins two complete ideas: "Tris Imboden has drummed for Stevie Wonder and Julio Iglesias" and "most know him as the drummer in the band Chicago". When a conjunctive adverb is used for two complete phrases, a semicolon needs to precede the conjunctive adverb. The conjunctive adverb is correct because it is showing how people's knowledge of Tris Imboden is often not complete.
