@Eusebius Punz
I think to get more constructive feedback now, you should go take 10 pictures with camera/phone of dish, mounting bracket, current LNB/feedhorn etc, and post them here.
To help you further, the Forum will need more details on your dish than the sales advert from 2 years ago.
From the willhaben picture, the dish looks like any >1m PF dish with a couple of feedarms slapped on, they don't even seem to be evenly spread out around the dish.
Without those one or two levels of details more, my best advice can only be "try the GI LNB, and see what happens".
Don't get me wrong: We're several (unrelated) individuals who would like to help, but we need a bit more information to go on - we can't use the Force or anything like that...