Python toolbox running old version of script when working in old MXDs

[IanRolls]

I am using ArcMap 10.2.2 and have noticed that after updating a Python script for a tool in a Python toolbox, the tool will automatically update when run from a new (blank) mxd but will revert back to running the previous version of the script when opening previously saved mxds- but not all. Has anybody else noticed this type of behaviour? I am using a Windows 7 machine running Python version 2.7. It would seem that for these particular MXDs the previous script is held in memory. I have tried reseting the normal mxt file/refreshing the toolbox but no joy.

Many thanks in advance.

[Zeke]

Maybe your new script at 10.2 is running updated arcpy not available to earlier versions? Just a thought. Do your old scripts still exist, or have you deleted or moved them?