Reusing CSC when changing the transmission?

[Ben370]

I put in a new clutch kit, Zspeed CSC, and master cylinder early last year.

Now it's rough going into gear and the rear section of the trans has a small leak so I know that's bad.

The service manual says to replace the CSC whenever changing the trans but it that necessary with the Zspeed one?

TM-12
Never reuse CSC (Concentric Slave Cylinder) body and CSC tube. Because CSC slides back to the
original position every time when removing transmission assembly. At this timing, dust on the sliding
parts may damage a seal of CSC and may cause clutch fluid leakage.