I have a turn-of-the-century house of a split-level model where the basement wall is made of natural stone of varying sizes about 1 meter thick. However, the house has settled at one wall, and I took the opportunity to look at it from above in the living room after removing the floor and tearing out the floor joists. It turned out that there were cracks on the top of the masonry basement wall. It proved to be about a couple of centimeters of cement. The wall seems to consist of stacked stones that make up the outer part of the wall and similarly for the inner wall. Then, there are numerous stones of varying sizes in the middle.
(I unfortunately can't see the wall from inside the basement as a brick wall has been built inside).
My question and my consideration is: Can you remove the loose stones in the wall and then fill up with concrete and reinforcement to get better stability in the wall??? The natural stones should then lock together, and it would also eliminate the draughts that storm through the wall since it is not very tight. I feel like it would make you feel a bit more secure...