Rock obstructing, need solution for the placement of borwell pump at 100 ft

Sir,

We have 150ft borewell, we inserted 1hp texmo motor but we are not able to insert after 40 ft. I think some stone is there that's why motor is unable to go after 40ft. So we decide to set the motor in 40ft, but we want to insert it atleast at 100ft. So if any one know how to remove that stone please tell me.

Thanks

Manoharan