On 21 October a party of eight, including Robert Preyer (23) and Ted Lenz and David Voegeli (both about 19) visited Wind Cave, in Pennsylvania, which is unusual for being developed in schist as the result of slumping. They entered the cave at about 10:00 AM
At about 11:00 AM, Preyer, attempting to squeeze through a narrow passage to the rear of the south passage, became stuck with Lenz and Voegeli on the far side and could not release himself. A rescue squad was called for aid and tools. He was released with the use of a hammer and chisel.
NSS Cave Accident Reports, 1968, Page 4.
A minor incident, but one which could have been serious deeper within a difficult cave. Preyer attributes the situation to "overweight and overconfidence."