Clutch pedal sticking to the floor

Hi everyone, I don't own a GTI, I'm posting this for a friend who is facing this issue, his clutch pedal started sticking to the floor, he have to use his foot to bring back the clutch pedal.

I think his slave cylinder is failing, what do you guys think it could be, he is planning to open his transmission soon.

Thanks for reading and for your help,
Have a nice day

Kind regards

Bleed it some more.

Cadubya said:

Bleed it some more.

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He told me that he already bleed it and added oil to see if there is a leak and he noticed no leaks.

FlowMK6 said:

He told me that he already bleed it and added oil to see if there is a leak and he noticed no leaks.

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If there's no leaks then there has to be air in the system.