My wife and I are considering purchasing a new house, but the surveyor says that it has wall tie failure. What is the best solution for repairing this? Is it really necessary to get the old ties out again?
Let me first say, being originally from the UK my understanding of "wall tie" might be different from your particularly definition/situation.
"The wall is brick on the outside and block on the inside" that to me describes Cavity Wall construction ie the outer and inner leaves of brickwork/blockwork are tied together with wall ties, normally spaced at 450mm centres vertically & 900mm centres horizontally (spaced differently at openings).
How does the surveyor know the wall ties are failing?
Are the walls bowing in or out or are the walls cracking?
See if this helps, How to Replace Wall Ties
If the above link does not help &/or I have got the wrong end of the "wall tie" stick, please post back with any additional information you may have.