Convergence IC has gone out most likely. After searching for a couple days to fix my own TV, I'm finding that this is a common problem for Sony Rear project CRT TVs. The TV has two convergence chips and should be changed at the same time. Here are some links from my current research.
http://forum.videohelp.com/topic320189.html
http://techlore.com/forum/thread/17742/sony-KP-51WS510-convergence-ic-help/
hype8912, July 2007