Brick mortar is very crumbly below the damp course.

[tryall]

I have recently moved into a 1960's bungalow and the external brick work, particularly below the damp course is very crumbly.

Do I have to rake out all of the mortar, as this I think will make the bricks rather loose, in fact I believe I could remove the mortar to the depth of the brick.

Also what is the best mortar pre-mix bag to purchase