Function of the card:
Ctdl 3 way and npn field replacement
Three-Way +AND (no loads)
CK is listed in some sources with part number 371270, which corresponds to CKWF.
Field replacement part number: 370978
Image courtesy of Henk Stegeman
The information on these pages comes from a variety of sources, especially old IBM documents on bitsavers.org, as well as information from the IBM 1401 restoration team, especially Tim Coslet's SMS data and Jim Hunt's data. Much of this information was obtained through OCR, so don't expect complete accuracy. These pages are not associated with IBM in any way.