I had a Pioneer Elite do that once. Service company spent months in and out of the house. Kept jumping back out of convergence. They hauled it into their shop. Worked with Pioneer for another month on it. Pioneer finally gave up and sold me a newer model at a discounted price.

From my experience, I would say call a service company and if they don't fix it the first time, it's shot.

I eventually migrated to a Plasma and I love it.