You could make the width of the connector tighter by wrapping it with duct tape if that will make it snug,
Can an IEC socket be too short?
I recently replaced the female end of my custom power cable because the previous plug seemed to not be very tight. It was super easy to cause my Luxman integrated to lose power with just a little motion (1-2 mm).
Well, the new plug does exactly the same thing. So now I’m wondering, is it possible for an IEC socket to be too shallow, or have pins that are too short? Or could it be that because the equipment lacks a ground pin I’m missing grip strength?