Hi!
I'm pretty sure your lock was manufactured by the German company "Burg Wächter" and I have a 4-lever padlock which is probably very similar to yours:

Since it is a lever lock which you preferably pick with a Hobbs pick, there is no other way than to use 2 tools. One to tension at the back and one to lift the levers. These locks tend to have very strong springs so maybe that's what made it awkward for you.
Take a look at this video to see what's going on inside the lock:

There might also be the possibility to impression your lock with smoked blanks (given that you got some that fit)...but that's another story...
Good luck!
peace,
scholls