Roller Shutter Tensioning

[Gaverick]

Anybody know anything about how to tension a roller shutter on a workshop unit?

I've recently moved in to a new unit and the door won't support itself in the open position.

 

[DXP55]

I just googled "Roller shutter tensioning"

 

[Pumpkin]

Is it a wooden one in sections? I fit those. There are loads of different ones, but they all work on the Principle of holding the centre bar still while adding turns to the spring. Under no circumstances loosen the spring off without having something to hold it in place first, if it hits you when the tension is flying off it could seriously hurt you.