Loose fitting power cord.

Wrap the Teflon plumber’s tape around the termination of the PC. This will make it fatter and will be a tighter fit. I have used this method many times.
If the cable is extremely heavy, I use a block of wood or heavy sponge rubber underneath the cable behind the component.

Electrical tape is the first method I tried and it’s a bitch to clean it all off. No adhesive on Teflon tape and it's resistant to heat.

@noromance
Makes sense, but some of these aftermarket cables make a tight electrical connection. It’s the smaller size of the molded termination that creates wiggle-room in the IEC.
This is the case with my Audience PC’s.

However, the OP's cable seems like it's not a tight connection.