The chimney is about 23 feet tall and naturally the part needing repair is not accessible by standing on the roof. The photos show the repair areas and I also might add a concrete overhanging crown if I can't repair the old one. The other sides of the chimney are in much better shape and need only minor repointing. Is there some kind of ladder stabilizer that might work - the stabilizers I am familiar with are hard to use on a chimney because the support feet force the user to be quite a distance from areas needing repair, meaning I have to do lots of reaching. I know the right answer is to set up scaffolding but it would take lots of stages and I'm on the gable end which gets complicated, time consuming and expensive.