Due to advancing age and Mr. Carter's wish to concentrate on mining equipment, the cave was put up for sale in 1965. Two business men (Burke Malcom and Bruce Prather) purchased the caverns under the corporate name of Mal-Pra on April 18 1965. They decided immediately to close the caverns temporarily to replace the 1910 stairway in two-thirds of the cave. The exit Where Mr. Mercer fell so many years earlier was not to reopen until 1982 as the exit had filled in with dirt, rocks and crumbling walls.

In 1972, Mal-Pra Corporation replaced the lighting installed by Mr. Carter and with the additional lights for the exit, there is a total of 88 lights today. Colored floodlights are used throughout to prevent the growth of moss which grows under white lights (they make "artificial sunlight"). It is necessary, however, to have some white lights on the extremely steep stairs in order that the public can be sure of their footing.

The cave reopened to a depth of 161 feet on June 5, 1965 with a combination of concrete and wooden stairs plus walkways and platforms. This eliminated any climbing over the rocky floors. These structures were designed to safe-guard the public, using modern materials and methods surpassing the guidelines of the building codes. All wooden stairs are checked on a regular basis to detect and correct any problems from heavy usage and dampness. In 1981 all support beams and timbers in the caverns were replaced as a matter of course.