Think I'm going for the external small monitor option, my fault has reverted back to "normally there, occasionally not" mode.

For those who are interested, the OEM part number on the back of the LCD module is "ARIMA Display Corp mc57t02E". I can find this in the UK for a mere £400 (makes Yamaha look cheap!) or from a hong-kong supplier on eBay for about £100 + postage, trouble is the picture they've got may have the same part number but the connector looks different. Therefore not worth the risk given that I can get a small TFT monitor for less than that today from a local supplier and ergonimocally moving the display to somewhere nearer my eyeline has a certain appeal.