Uneven performances and weak direction keep August Wilson's Pulitzer Prize-winning "The Piano Lesson" from reaching its full potential in the new production for The Actors' Group.

The actor called Q does excellent work as Boy Willie, a quick-talking country boy intent on selling the family heirloom piano — fashioning a convincing self-taught con man who repeats his mantra and expects everyone else to believe it too.

But Tamara Halyfield as his citified sister Berniece fails to sufficiently push back to hold on to the instrument — creating the unsatisfying tone of someone battering against an absent center.

TAG's fledgling director Jeanne Wynne Herring struggles to manage timing in those confrontations and doesn't capitalize on the fight scene that ends Act One or on the exorcism that is the play's big climax. She also could tighten up the three-hour running time.

The frustrating result is that we watch the play's power waste away in its most significant scenes — and are helpless to put it on the right track. There are, however, scenes that are well done.

Set in 1930s Pittsburgh, the piano is a slavery remnant, carved with family images and portraits of the slaves who were traded to buy it. Not only does it visually encapsulate Berniece and Boy Willie's history, it has additional significance since their father died while stealing it back from the white family that owned it. Associated spirits permeate the house.

The script is short on plot, but rich in history, dialogue and character. The best in this production comes from the interplay between Boy Willie and other males.

Uncle Doaker (Curtis Duncan) lives with Berniece and is sucked into the feud. Whining Boy (William Ammons) is a charming but shiftless gambler on the lookout for a handout, and Lyman (Demetrius "Pono" Jones) is a simple soul prowling for women, who comes north with Boy Willie to sell a truckload of watermelons.

Together, they create a rich patois of street slang and comic irony — culminating in two spontaneous sing-alongs that stop the show with their musicality and dramatic impact.

TAG makes good use of its playing area with a layered and historically detailed set designed by Andy Alvarado.

But despite the success of banter around the kitchen table, those scenes don't carry the production, which sags when it should zero in for the dramatic kill.