The service manual is out there but just in case someone knows of a source for an operators, preferably for the DSA524. There is apparently a paid-for sourxe which I may go for. There are 58 buttons on this unit, for a start significance of the grey and blue buttons and the specs for ext trigger. Just pointers to, please, no large files sent to any email accounts of mine divulged on the www should anyone have a pdf etc , they will be rejected