Machine screw mystery: oval head over circle flange

[Quourteous]

Hello All –

I came across the machine screw in the attached photo today. The oval head is about 5x4 mm, integral with the circular flange underneath, diameter maybe 8 mm.

If the head were exposed, I would just undo it with a pair of pliers; but as we see, it's down a cylindrical recess, maybe 15 mm deep – in the base of an old Krups coffee percolator, fwiw, that I'd like to see if I can fix for a friend. My slimmest long-nose pliers won't open wide enough to grip the oval, inserted into the recess.

Any clever idea how I could unfasten the darn thing? Thanks...

 

[Quourteous]

FWIW All, the screw seems to have been an idiosyncratic Krups-only screw deliberately made difficult for anyone to unfasten, to deter anyone not 'authorized' to try repairing their machines. I eventually cut out the recessed channel in the plastic base around the head with a Dremel. The base then came off easily – and later fitted back with the clips around the edge without any need for the 'deterrent', 'security' screw.

Meanwhile, I messed around with the electrical connections inside the unit and as expected, one had become a bit loose over the decades the coffee maker had been in daily use. I re-tightened it and the machine is working perfectly again.

 

[Meadowlark]

DIY success.