When Bob and Jane Cull returned to court last week in their decade-long legal battle against homebuilder Bob Perry, it was like starting all over again. Jane Cull’s “nightmare,” as she calls it, has been bouncing from court to court for years. “We’re just wondering, when will it ever end?” she said the other day in downtown Fort Worth, where their case is back in district court. Again. The Culls are a retirement-age couple who say Perry Homes built a defective house with a broken foundation and cracked walls, but won’t fix it. The Mansfield couple took their case to arbitration and won an $800,000 award — but Perry refused to pay, saying the couple had waived their legal rights to arbitrate.