"He said fill it with why you're never going to steal again," Castillo recalls. "And when you're in that room filling out that notebook, I want you to think of something that's gonna keep you off the streets and out of trouble or you're never coming out of that room again.
"We came home, started a band that day," Castillo recalled.
During the next few years, Castillo learned to play the guitar and the keyboards, specifically, the Hammond B-3 organ. He became so fond of the instrument that he sought out the B-3 when the group was away from the club.
"We were doing a Fourth of July weekend at the Alameda County Fair," Castillo recalls. "We were opening for the Loading Zone. And, they had a very good organ player - he played a big B-3 organ. So I asked if I could borrow it."
Cautious, the Loading Zone sent their roadie to check out Castillo.
Stephen (Doc) Kupka asked what Castillo's band was like. Castillo said the Motowns were like the Spiders, a popular East Bay soul band. "Oh," Doc said. "You can use the organ."
After the Motowns played, "Doc says, 'You've got a really good band. There's only one thing wrong. Your horn section, it needs a little bottom. By the way, I play baritone sax and I have a Selmer with a low A key.'"
Castillo invited Kupka to come for an audition the following Tuesday. Naturally, Castillo forgot about the invitation.
"We're rehearsing in my garage and there's this banging on the door," Castillo recalls. "It's Doc. And, he's there with this big horn."
"The guys are going 'Who is this guy?' I said, 'I told this guy he could audition."
"The next thing they see is this long-haired hippie coming through the window with a baritone sax."
Kupka played his first gig in August 1968. Forty-three years later, through commercial success, critical acclaim, countless personnel changes, drug addiction, near breakups and shifting musical tides, Castillo and Kupka are still the core of Tower of Power.
Tower of Power
8pm Friday, October 21. Tower Theatre, 835 NW Wall St.
Mike Ficher is host of the Ultimate Oldies Show on 88.9 KPOV, Mondays 10 am and Tuesdays at 8 pm