Maryo -

Old leaves? Young leaves? How long ago did you repot it?
Can you make a pic?

If it is one and only one plant - you are doing the right thing - root the leaf and dispose of the old plant. Most possibly something wrong with the conditions - too cold, too much fertilizer in a soil, Ph gone out of the desirable range etc. And this plant is just the most sensitive.

You can leach it, repot it in a fresh soil and baby it a bit, but usually it takes forever to grow out of the damaged look.

If you post the pics - I am sure somebody will come up with a better diagnosis.

Irina

What do u mean by leach irina_co?

Found it irina_co ; )