Clean any access glue from the plates.
Check the springs are equal lengths.
Check the clutch basket doesn't have any nasty ridges. If there are any gently file the worst smooth.
Put it back together and fill it with 5W-30 fully synthetic oil, that's the stuff I use.
I don't have a lightener and use the original Domino levers.
Adjustment is tricky and difficult to advise on but you should be able to get it working nice, changing gear, not slipping or dragging and have a small amount of free play at the cable. Get the engine warm before you start. You may always have a tiny amount of drag but nothing more than a slight slowing of the engine tick over when in gear at standstill. Not jerking forward with the clutch pulled in!
Once sorted they are good and reliable. Good luck and stick with it.