[AccessD] Data source for PivotTable-Form in ACCESS 2000

Hi, this drives me crazy,
4 years ago I defined in an ACCESS 2000 application a "PivotTable-Form". The
resulting EXCEL table inclusive the "Data update" works perfect. I now want
to update/change the query for the "Data Source" but cannot find which query
is behind the  "PivotTable-Form" or behind the resulting EXCEL spreadsheet.
When editing the  properties for the "PivotTable-Form" or the EXCEL
spreadsheet the "Data Source" is  always blank.
Question: Where does Access 2000 or EXCEL 2000 hide the respective data
source  (Query)??

Helmut