I was lucky enough to be in the Chicago circuit when they were still in the clubs. I saw them dozens of times at Haymakers, and a few times at Night Gallery (main act played from 2:00 am until 6:00 am). In a club setting, with 3 sets, they were brutal. It was non-stop. I couldn't take more than a set or two, but always felt they would be a great concert act. Back then, Nielsen NEVER EVER played a lead in three sets of material. It was all chords and inversions. It's the reason I have always said how underrated he is as a guitarist.
Here's one of their first videos, shot at Night Gallery during an afternoon, when the club was usually closed.