Thanks Dave,
It's a 17MB70-5P main board with a heat sink covering the M/proc. Noticed similar with Sony 'EX' series, where the heat sink always indicates SSB death, and unlike LG you can't cook 'em to perfection.
Noticed several on Ebay, but they're hens teeth, and usually 42 inch versions up at £65.00 plus. As it's a 2009 set, don't think to bother.
Guess a known SSB issue, though I usually like Vestel if I get the panel codes right - Chris.