duegi - your 2.3 serial numbers place them before the upgrade at 4567 which added a bucking magnet to the back of the midrange coax. That magnet has two principal effects: 1-greatly reduces stray magnetic fields to decrease interference with a TV, cables, etc. 2- the magnetic field is more effectively focused in the motor gap. It sounds cleaner.
Rob at Coherent Source Service could tell you if and/or how to upgrade if needed or wanted.
Historical note: The CS2.3 sported the first iteration of the passively coupled coax driver which was then applied to the PCS. A few years later it wad further advanced along with advancements to the woofer which became the drivers for the CS2.4.
