Adjusting the door closer

[NorthernLights811]

In my building the door slams every time it closes.
I tried adjusting the speed of the door closer, but the instructions show 3 points of adjustment, whereas I only managed to find one (the side one) and adjust it with an Allen key.

Am I missing something? I can't find the rest of the screws that the instructions mention!

 

[ronniecabers]

Well looking at those instructions on it , it looks like they should be on the top of the unit , the other end to the Allen key adjustment, the one picture that isn't there lol. There is a very good possibility though that the oil has either leaked out or lost its viscosity and no adjustment will work