What's an Luk ? Those lines can be very difficult to push in. The slave has one that has to be pushed in to release, and, the clutch line has one that has to be pushed in to release, between the two it can be very difficult, specially when you're flat of your back and trying to just reach it.
The last slave i got was a Power Torque CS2248, from Oreilly's I believe. It connects different from any others I've seen, although it is still very hard to push in, it has a notch on each side for a lock pin that slips in behind a collar on the line connector, and you can shine a light there to see when the collar clears the notch, then slip the pin on and it's there. I really like this one best, even tho it's still rather difficult to get in
Well, I would post a picture of it but see no way to do that now :/