Yes, you have to use the original Chrome downloader. You can get to it on the INCOGNITO window.
1. Ctrl+Shift+N OR Menu -> New incognito window
2. Ctrl+J OR Menu -> Downloads
3. Then find your failed/paused and click the giant blue RESUME button.
This should be a simple feature to add to the alternate download manager if it does not exist since you just have to link to the function, if it exists it just needs to be documented where it is and make the function more obvious and easy to access.