Hey, @juliust9149185. Welcome to the Photoshop Community. I'll help you figure this out.
You'll need access to the old machine to manually move the Brushes to the new machine. Do you still have Photoshop on the old machine? What operating system were you working on?
If yes, you'll need to:
1 - Group Presets in the Window menu > Brushes panel in Photoshop.
2 - Select a group > Menu button > Export Brushes to output your Brush groups in .ABR format.

3 - Move these ABR files to the new machine & double-click on these ABR files to import.
If you don't have Photoshop on the old machine, you might have the Photoshop Settings folder.
1 - Navigate to the Photoshop Settings folder. (Location for macOS & Windows: https://adobe.ly/3Hbbnnh.)
2 - In the PS Settings folder, copy the Brushes & any other PSP files & overwrite/paste in the new machine at the same location.

Let me know if this helps. Thanks!
Sameer K
(Type '@' and type my name to mention me when you reply)