Defeated by small bits of plastic

I have managed to get the back of the kiln off and remove the old thermocouple from the firebrick hole. This was relatively straightforward; 12 screws to remove the kiln back and 2 different ones requiring a quarter inch spanner to get the ceramic block thing out of the firebrick hole (if a woman designed this, one tool would do both jobs). I've got the new one in place at the back now but attaching it at the other end to the controller is causing some grief. The instructions just say to "Remove the old thermocouple wires attached to the back of the controller".

The photograph above shows the back of the controller and the old wires - I have no idea how to get them out. It looks like I have to remove the bits of plastic first. They don't look like they unscrew (though I have tried).  Another tack was to grab them with pliers and pull but all that has done is chew the plastic up. Before I ruin it completely, I have sent a photograph to Cherry Heaven and hope they have some advice of how to do this. I am thinking there is some kind of trick to it that only men know. I am thinking I should've just ordered a new kiln by overnight carrier, it would've been here by now and I wouldn't be left unable to make beads at the busiest time of the year. (Yes, I am grumpy AGAIN!)

I am going to make myself a nice lunch and watch Bargain Hunt to cheer myself up.