I have not noticed the same thing with the 5402 M3 I bought recently - sounds like either the mains inlet aperture in the chassis was not punched correctly (but that is unlikely, given modern production tools and methods) or the wrong main-inlet module has been used, and that would seem more likely as many slightly different such components are available to box manufacturers.
In either case, this is a potential safety hazard as the inlet module could eventually work loose and expose the live terminals on the inside. This is especially dangerous as the 5402 is a Class II Double Insulated product and so there is no safety earth connection to the chassis or earth conductor in the mains cable.
Personally, I would do two things:
- Immediately contact the supplier with details of the problem and request a replacement (which will hopefully not be the same!).
- Also contact the UK Trading Standards (via the Citizens Advice Bureau which handles all the initial contacts on behalf of the TS) because this problem could affect many more receivers across both the UK and Europe - and TS can initiate an investigation with your supplier and the importer which brought the receiver into the UK. That, in turn may result in a product safety alert or recall - the size of which would depend on the number of receivers which are found likely to be affected
PS: take photos of your receiver, including the serial number, before sending it for replacement, and give those to TS when they contact you, because those photos will enable them to more clearly trace other faulty units.
