At the Go-Go's reunion gig Tuesday - the all-girl band's first full-length concert in five years - memories of how good they once were suffered a head-on collision with reality.

The punks in pink played a 15-song set gleaned from their handful of albums during an after-work show at Midtown's China Club, sponsored by radio station WPLJ (95.5 FM).

Members of the quintet, which made its mark in the early 1980s, have had varying degrees of success as solo artists since disbanding in 1985. But in the last 14 years they've had an on-and-off relationship with one another.

Appearing again in their original line-up, the Go-Go's were pretty much on the money throughout the evening, opening with a driving beat set by drummer Gina Schock for the instrumental "Surf 'n' Spy." As Schock, a k a Thumper, pounded away, singer Belinda Carlisle made a star entrance, dancing to the tune.

If Carlisle's voice were half as good as that entrance, the show might have been a home run. Unfortunately, the woman's pipes had way too much rust in them.

On "Head Over Heels," for example, there was hardly any power in her singing. To make matters worse, the sound tech had only half of the China Club's PA system turned on. Eventually the right switch was flipped - providing startlingly better amplification - but Carlisle's voice was still weak.

Whether it was because the tech found the right knob or because Carlisle found her confidence (thanks to the friendly fans or the beers she demanded from them), the band eventually did begin to click, launching a no-holds-barred closing sequence that started with "Cool Jerk" and moved through "We Got the Beat."

Still, as they played favorites such as "Beatnik Beach" and "Our Lips Are Sealed," one thing was painfully clear: Carlisle was so off key it made you cringe.

She also seemed reluctant to share the stage with special guest Melissa Etheridge, who was called out from the wings to join the band on "Our Lips Are Sealed" but had trouble getting into the mix.

When Etheridge finally did get a chance, taking the tune's lyric bridge, "Hush my darling ...," she raised goose bumps with just a few notes, showing in a short burst a range that surpassed Carlisle's.

The crowd, a private group of WPLJ listeners who got free tickets through on-air contests, seemed happy to be there, and glad that the Go-Go's were playing. But it was the surprise appearance of Etheridge, who was in town to do the Letterman show, that got the biggest cheers.

If this was the best concert the Go-Go's could muster, it's probably best that they were gone-gone for all these years.