There are two different types of secondary mirror assemblies on Celestron 14" SCTs. Newer models have three screws for collimating the secondary mirror, while older scopes have these three screws plus an additional central screw that holds the secondary mirror. See image below.
Above: The old style Celestron 14" secondary mirror assembly has a fourth screw hole in the middle that holds the mirror in place. New style scopes have only the three outer collimation screws.
Before purchasing a C14 conversion kit, we need to know which configuration your telescope has. Please contact us if you have any questions.