Borewell casing damage in Hyderabad, AP -Is re-casing or re-boring an option? Advice required


My builder has dug a borewell of 4 and half inch size in loose soil area, generally in this area water is struck around 40 ft. The borewell in my case was dug to 260 ft, with 70 ft of casing and the motor kept at 230 ft. Water level is at 15 ft in the well currently. Due to some problems with pumping the motor was being recovered when it got stuck at 60 ft. Fortunately the motor was recovered using chain/block by an expert. He advices that for 15 ft (46 to 60ft) the casing has buckled and will prevent re-insertion of the motor. Also opines that the casing be "expanded" using a borewell machine.
I am looking for guidance regarding what this procedure involves. Or is removal of the casing and addition of new one needed (recasing) ? A few others advice on digging a new borewell, but in my case space restrictions are against that.

What are my options in this case?
What was the cause for the buckling of the pipe? (quality of casing?)

Your valuable suggestions are sought on what further action I should follow.

D. Partha Sarathi