I never used that type before so I'm unsure the problems they may have. Did you take it back off and make sure the rubber washer is still inside the supply hose?
I didn't get that far today.
But I think I FINALLY have solved all the problems!
I started today by draining the water and working on the problem stainless line.
I was going to loosen the part at the top that clicks. I kept turning it counter-clockwise
and it kept clicking which was very annoying! It didn't want to come loose.
So I left it alone.
Then I concentrated on the part above it, that screws into onto the vertical column that goes into the tank.
I tightened it, but before I did, I moved the ballcock into what I thought was the correct position.
A position where the ball cleared both the vertical column and the tank's side.
After I tightened that nut I tried it out. Opened the water and flushed.
After the water drained I noticed that ballcock arm had moved all the way over again,
and was now actually on top of the vertical column!
It seems that's where it wants to be all the time!
I had the same ballcock in my main toilet but have since changed it for a newer system.
But I used to position the ballcock in that same tight space. The space where it just clears the
vertical column and just misses touching the side of the tank. Maybe 1/4" max. clearance each side.
Well today I think I learned where it wants to be and how it functions.
It stays in the same position, above the vertical column.
When the tank is flushed, the arm simply rests on the flat part of the vertical column and waits.
Then when around 80-90% of the water has filled up, the water begins to touch the ballcock and it
starts to rise. Soon after the water reaches the water line and the ballcock senses the correct position and
the water stops filling.
I've tried flushing now 2-3 times and have checked for leaks. Nothing yet after 1-2 hours.