Old Vailant no Filling Loop

[Hearts123]

Hi I have an old Vaillant in a flat I cant find the model number but I'll post pictures. It has no Filling Loop so trying to find out how to fill it.
Trying to find out from the pic below which to turn to get it filled. The tenant previous said he used a screwdriver to turn soemthing

 

[CountryFan]

Looks like a TurboMax, I can see in the 3rd photo a braided hose, can you follow that and look for very small black levers? Failing this, could be an external type.

 

[denso13]

 

[Hearts123]

Thank you denso 13