Speedbrake doesn’t deploy (anymore)

[Hiob]

It did at some point and I can see the button animation in the cockpit but the brake refuses to come out.

Is there anything that inhibits the use of the speedbrake, that I‘m not aware of?

[AdrianL]

From P57 in the manual:

"Speedbrake operation is not possible with the centerline tank installed, or gear down.  
In case of general electrical failure, the speedbrakes retract automatically"

[Hiob]

Thank you, I think the canter line tank was the issue. Who would have thought of that…..