The only possibility is to move the rotary-valves manually by hand. additional you need a manual foot pump to generate hydraulic pressure.
We call that option "manual override" and you can order this additional with our C6 column (but not for a afterword upgrade)
An example you can see on the foto.
2) We are able to plug a second handcontroll on our new electronic, but it is just a "double" of the first one, in case of the spiral cable is broken or you like to use the system from 2 sides.