A friend gave me the 20" version of this monitor over the summer with the same issue. I thought I could find a replacement hinge on ebay or other secondary market. No luck. They were either for the wrong size or too expensive.
I had the thought of putting it in a fixed position by tapping it with a screw, but it is not made like that. Where I thought I could tap is only plastic. No luck, but a thought. Reverse it.
I turned the hinge around. You need to slide the ferrite filter to the other side. There are three index marks that will need to be filed down. Screw it back down and replace the cover and stand.
It now seats on my desk at little greater than 90°s, no slide. Gravity should keep it from coming forward.
Ok, I could have tried to set it as it was by tightening the nuts on the ends of the hinge. But I could have over tightened (not mentioned in the manual) and snapped them off and/or it might still be loose.