About 10 years ago we had the back garden flagged. Over the last 2 or 3 years a couple of flags have risen up slightly above the adjacent ones.Is there a way that something can be slipped down the gap to get under the flag and lift it so that I can scrape whatever is underneath and make it flatter (The offending flags are right in the middle of the garden!!!)
Depending on the gap between slabs, I have used a couple of old woodworking chisels. Push one down half way, lever the slab, push second one under the slab, lever up and use something longer to lever further.