From the moment he peeped into the orchestra pit at the Pacific Northwest Ballet's annual "Nutcracker" performance, Eric Verlinde has been driven with the desire to play music. These days, he's doing just that — and lots of it. Boasting one of the busiest gigs calendars in town, you'll find Eric working Sunday nights at El Gaucho with singer Josephine Howell, Monday nights on the same stage playing solo, and every Tuesday night he leads one of the city's favorite jam sessions at the Owl &