I feel your pain, some have great success with the Diage, we had terrible luck like you,
broke down and bought a GBC Titan, while more money it has more than paid for itself in not having any ruined prints, and fast to operate. After I got the Titan, I was going to scrap the Diage, but decided to use it for mounting prints, which it does an excellent job.
If you are not in a position to replace it, read every thing here on the search for Diage,
then contact the ones who are using it with great success. Good luck on your qest!