Easiest, most effective, and clean solution without replacing the chassis receptical or your plug end is to simply start with a single layer of black electrical tape wrapped around the male IEC portion that enters the jack.. If needed you can build up with another thin layer of tape until you feel it is snug enough, warning however this can get VERY tight fast and difficult to disconnect, and can of course "Bunch" the tape up if you disconnect a time or two and force you to replace the tape as it will not go back in...
You can do the same as mentioned above with 1.25" heat shrink I think is the ID size, but don't quote me I can't remember the exact size off the roll.. This however is the same issue as electrical tape once it gets bunched up once or twice can need to be replaced.