Wattgate IEC does not fit tight.

I have the same problem with wattage connectors. I just rubber-banded the connecter to the footer of the DAC to which it is connected. 

When I put together a power cord using Wattgate I was sent a little plastic tube to sit between the positive and negative blades to add bulk and tighten up the connection. Pretty poor excuse for a fix. And yes, the assembly screws are soft too.

Not sure about the Wattgates, but these inexpensive 'iec inlet tighteners work for a variety of PC / components and are easy  to try:

https://www.amazon.com/dp/B0771T7PC9?ref=ppx_yo2ov_dt_b_fed_asin_title

It would help to know what amp the OP has.

Example: Reading some posts of the OP’s.

Mark Levinson - No 585 Integrated Amplifier

I don’t think any audiophile power cord will fit properly on the ML 585.

The OEM or a cheap $6 computer cord will work fine.

The IEC keeps disconnecting from the amp due to not fitting tight. I replaced it with a 350i and it won’t even connect now. It seems the part that connects to the amp are too far inside the IEC. It falls out immediately.

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It is a Levinson 585. Do they use a different socket? It is strange that a $6 generic cord works but the audiophile IEC will not.