For a while, Schenker’s volatility kept drummer Parker, the band’s voice of reason, from rejoining the band. “Michael just wasn’t stable enough for me,” he told me. “I’m the kind of person who wants some stability. I want to walk out onto that stage and know we’re going to finish the set, and we’re going to enjoy it—rather than someone’s going to chuck their guitar down and storm off and we’re not going to see him for six months.”

Which is exactly how one tour ended, as Mogg told me over beers in the lobby of Chicago’s now-defunct House of Blues Hotel.

“We were in Tokyo, toward the end of the tour, and in the middle of the fourth or fifth song, he just smashed the guitar on a pillar and went off,” Mogg recalls of Schenker. “And it was Japan, so it’s not like the U.S. or Europe where people would boo or jeer. It was complete silence. You could hear a pin drop. Your mouth just drops, and you’re like, ‘Oh, my God ….'”

The band hustled offstage, Mogg continues, and “the promoter’s going mad, and he says, ‘Someone from the band has to go out and explain to the audience or apologize and tell them what’s happened.’ I said, ‘I’m not going out there.’ Me and Andy said to Pete, ‘We’ll give you so much money if you go out there.’ So Pete went out and explained what happened, and that was that. It more or less screwed us in Japan.”

Now, everyone has moved on. Schenker is playing smaller venues with a guy named Doogie White on vocals, while UFO has brought back three-fifths of the “classic” lineup: Mogg, Parker, and Raymond, with respectable player/shredder Vinnie Moore playing guitar. (Way and UFO have decided that a reunion is probably ill-advised for both parties.) Are they solid? Sure. Transcendent? No. But it works well for Mogg, now 66 years old.

“We’ve got a real good vibe,” he says. “I know we’re going to do a gig tonight, and there’s not going to be any drama. Everyone’s going to show up and do their part. It’s like, ‘Oh, this is good.'”

Spinal Tap IRL: The Brief, Sordid Reign Of '70s-Rock Legends UFO 

So it was all there: the talent, the riffs, the tunes, the brushes with greatness. But that big moment for UFO never quite arrived. The question still haunts the halls of rock history: What could they have been? What if Schenker had just maintained, just kept his demons at bay and stuck with the best band he ever had? But that’s like asking Courtney Love to keep it together—his instability is likely what made him so brilliant.

“Unfortunately, that’s now an essential part of his biography—The Troubled Michael Schenker versus The Talented Michael Schenker,” Morello says. “That’s a shame, but it’s not uncommon for people who are uniquely talented to be uniquely troubled.”

Jaurigui compares Michael to his brother, Rudolf Schenker, who played with Scorpions for more than 40 years. “Rudolf has had this amazing, incredibly successful career, but he’s a pedestrian guitarist. Whereas Michael is this super-genius guitarist, but he disappears for years at a time, makes records that are iffy at best, and plays with some really random bands. But if he could have just stayed in UFO, they’d all do much more business than they do on their own, and have a simple, happy life. It’s too bad.”

So if it were me—if it were my band, and I’d had the chance to reside among the immortals, but it all slipped away because my brilliant guitarist was afraid of success, or his lead singer, or whatever, I’d be furious with Schenker. Every day, I’d curse his pointless inconsistency, his inability to grasp just what he was throwing away. I’d also curse the fates that stuck us with an overmatched label, and of course, curse our own drug-addled short-sightedness. Sure, UFO gets the occasional nod—their song “Young Blood” plays in the 2013 Steve Carell film The Way Way Back, while “Doctor Doctor” made a Scrubs promo. But that’s cultural detritus. It’s not enough.

Yet Mogg—the only guy to appear on every UFO album—is much more serene about it. I’ve interviewed the wry, engaging singer several times over the years, and each time, I’ve asked him how he feels about UFO’s legacy. Doesn’t he feel cheated? Wronged? Pissed off about what could have been but wasn’t? I’ve come at it from different ways every time, but each time, he says no. Instead, he describes a near-zen-like acceptance re: his life’s work.

“That’s just the way it is,” he says. “There’s no point going in a direction of thinking about what could have been. There’s nothing you can do to change it, so you may as well accept it for what it is. And I’m quite happy with that. I don’t want for more than what is. I’m quite happy with what I’ve got. I enjoyed every minute of it.”

“I don’t weep for UFO,” Tom Morello concurs. “They made some really great records, and their live album is one of the greatest albums of all time. No one can take those points off the board.”

Joel Reese is a Chicago-based freelance writer whose work has appeared in SPIN, Details, Forbes, Texas Monthly, Chicago, and the Best American Sports Writing series. You can find his work on his website or follow him on Twitter.