I'm not knowledgeable about this model Montblanc, but the mechanism looks as if it works the same way that the MB Classique does.
You do not say what the problem is. Is it that the point does not come out, goes back in when you are writing or will not go back in when you twist?
It could be that the 'bent' end is preventing free movement of the refill. However, If it goes back in when you are writing, and assuming it is properly extended, then the mechanism is worn out. Look at the small plastic peg in the slot and see how it moves back and forth as you rotate the mechanism. You will see (if you have good eyes or a magnifying glass) that when it is extended it sits in a sort of 'cup' at the top of the cylindrical cam. If the cup is worn out, and you can only see the ramp, then the point will push back when you apply pressure as you write. You will need a new mechanism. I haven't seen one of those on *bay in the few years I've been hooked on pens, but that's not to say they do not appear (at a price!). Montblanc do not sell parts. I cannot see how these mechanisms can be disassembled.
The 'bent' end is most likely due to the barrel and grip section thread having been 'cross-threaded', unless you know otherwise. I'm not sure what the solution to that might be, other than re-cutting it with the correct size tap/die, whatever that might be. Look at the threads closely for damage.
Returning the pen to MB does not seem a bad option in this case - they will replace all damaged parts. And I'm the first to try DIY repairs.
You don't know what you need until you realise you haven't got it.