GU TB45e fuel sender wiring connection

[Outrage]

Hi, replaced the fuel pump as it's been playing up for a while now. In the process the negative wiring at the top of the sender broke flush with the plastic cap. (I attempted a solder job but that's been unsuccessful).

Anyone know the dis-assembly of the cap? It looks like a pop rivet from underneath, which I need to cut out and it should all come apart, but want to confirm before I start deliberately damaging things.

From above the wire of concern is the blue/red one which connects to the middle cap.

This vehicle has a gas conversion which was done prior to my ownership, its workmanship was very poor (and very wrong/caused fuel leaks, etc), most of the issues have been sorted but still fighting bits and pieces like this.

Am I right about how to remove the cap or is it held on another way?

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