Hello Chris,
     Thank you for that information- I have now been able to store the changes!
  Now all I have to do is hope that all of the epoxy glue I have had to use on the plastic 
 framework holding the PCB's holds as I put the case back on!  I assume that the heat
 over the years had made the plastic very brittle- lots of breaks as I moved the boards.
 Thanks again, best wishes , Mark.