HPS40 No Signal input

Hi I have an HPS40 since 2003 and today developed a fault.
Although the screen display looks fine but no wave-forms or value readings are displayed. (??? ad displayed as values)
the only display (wave-form) that is busy is when V is set to .1V/div.
2 questions if I may,

  1. any idea of what could be the problem#
  2. is there a possibility of a Service manual and or schematic.

Thank you in advance