I own two of the little devils..
Actually I really like them and have very little trouble..that said, I have been inside the turret on these units..not a simple setup for sure...
Sounds to me like you have more problems than a sheared key on the hydraulic pump..
Was this a sheared key on the hydraulic drive motor that drives the turret or the actual Hydraulic pump that is sitting on the tank..(the one that drives both the turret and the chuck close / unclose, plus other things??)
The turret is actually driven by hydraulics..(unless it is a newer model which has a servo driven turret)...and so is the Turret unclamp / clamp..
Do you have a parts manual??
If you wish, you can PM me. And either you can call me or I'll call you and see If I can shed some light on what might be going on...
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)