Opel Astra Accessory Correa Year 93 1.4

Hello good I would like to know a couple of things that happened to me this afternoon, first. The belt tensioner is gripped and makes a lot of noise (as is logical) and the state looking and I do not know where it is unstressed if the alternator or a roller that is located where the morro of the cox or of the roller itself that is gripped.
And second the roller that is gripped and seen that it is kita or apparently with a key of 16 or 17 but the screw itself will give me against the motor taco ... then to change it kite the engine taco?

If I am not mistaken that roller is the tensioner must have a hole where you can put or a key or a lever to turn it and thus be able to take the strap the alternator if I am not mistaken, I do not loosen if it is an Ecotec engine.-