Grout remover tool

Not tried one, but it's probably rather like using a "burr" in a Dremel. One issue is that if the cutter "catches" on something it will jump out of the track which you are trying to follow, generally hitting something you didn't want damaged. The technique is likely to be to try to use it at the lightest possible load.

yeah... I can't say I'm convinced by it either

NT

I'd be more inclined to use an oscillating multitool with a carbide blade. It would be much more controllable.

I've done that, and unfortunately despite careful use the edges of the tile s were chipped. Perhaps others have had more luck than me. The situation wa s partially recovered by ensuring the grout level was as high as I could ma ke it which mostly masked the chips.

As is usually the case, best to avoid the need to re-grout further down the line by using proper materials, i.e. a cement based grout and not some stu ff out of a tub which claims to be both adhesive and a grout. Sadly doesn't help if somebody else did the tiling.

Looks like it might be good for nose hair