The link from the Partha website leads to paid versions (or 30-Day Free Trials).
You can search the internet for the free version.
There are several versions that install in different directories.
I know two locations:
1. c:\\Program Files\\ON1\\ON1 Effects Free 10\\ON1 Effects Free 10.exe
2. c:\\Program Files\\ON1\\ON1 Effects 10\\ON1 Effects 10.exe
Partha applied the call from Gimp to version 2.
Where did your program get installed?
You have two options:
- change directory and file names (c:\\Program Files\\ON1\\ON1 Effects
Free10\\ON1 Effects
Free10.exe) or edit the correct path in the ON1EffectsFree10.py file on line 87.