Stripped thread on back plate

[csj]

I have just replaced a spur in my kitchen (water had got into the previous one from a leaking washing machine in the flat upstairs) and all works well.

However, the thread on the back plate (embedded in tiles) has stripped and I can not get a tight fit. Are there any "tricks " that I could use to hold the spur in tightly without having to remove tiles to replace the back plate/box. I have already tried using longer screws but they did not hold either.

Thanks for any ideas that anyone might have.

 

[oldtimer]

If you are serious about being an electrician then a tap and dwang as they say up here is a required part of your toolbox let me eplain I have had my dwang for 36 years with 3.5mm 4mm and 5mm taps no your box problem I had the same problem last week but I carry 3.5 mm extention screws (this is a male female set up and about 30mm long. Drill a 3mm at the back of the box tap it with a 3.5mm and the jobs done also a handy bit of kit is the 5mm tap because when you do a job in a old house the thread in a conduit box is either 2BA or 3/16 and most of the time the screws are too short or some numpty has jammed in a wood screw but you can tap it out with a 5 mm and again job done

 

[Marvo]

Sort of like an M3.5 spire clip?
I'd buy a pack of 10, but it would be a fairly rare purchase. The advantage of something like this would be no special tool required.

Just thinking out loud, I'm not too sure about spire clips, the only thing that holds them in place when the screw is removed is the tension. Maybe a hazard if the socket or switch was live and the screw was removed or missing.