Hi
@foglevel,
I would be happy to help! I will also add a ticket in to make sure that we restore the default Substance files upon uninstall so that the original plugin does not break.

The first step is to get max working back to a default state. If you have uninstalled all of the plugins and the updater (which it looks as though you have) first run the Substance updater which will restore the needed files for the initial plugin.
This can be found here.
https://forum.allegorithmic.com/index.php/topic,14223.0.htmlFrom here, 3ds Max should work as it had before installing the plugin. After this is confirmed, it should be as simple as running the new 1.0 plugin installer.
We also have updated the installer to prompt for uninstall but as it was not present in the original/beta uninstaller, for the first update, this will not be available. This process will be easier in the future.
Let me know if this helps and you are able to get it working.