Raise the cable off the floor until it's equal to the IEC jack. Since you've already raised them some, just stick something else under the lifters. You can also make a simple lift with strings & sticks in a variety of style, the easiest prob. being the Teepee style.
Also, wind some black electrical tape around the IEC connector until it fits snug into the jack.
Also, wind some black electrical tape around the IEC connector until it fits snug into the jack.