Adjustment of Zoo hinges for door drop

[Tbone]

Hi,

My outside door has 3 "Zoo" hinges,
The door is scraping at the bottom and needs a slight adjustment.
But, I thought I just needed to remove the end caps to get access to allen scrtew for adjustment. NBut I cannot remove the end caps, so I am not sure I am doing the right thing.

Picture is belwo.
Any advice is greatly appreciated.

Thanks

 

[crank39]

There is no adjustment as far as I'm aware, thses are just ballbearing butt hinges

 

[Tbone]

Ah, I see.
So, perhaps one of them has failed causing it to drop slightly ?
I did see some gunk coming from one of the hinges

So, if I replace it might improve ?