In the second image it appears that the main lead has died. The old growth looks bad but has 2 or 3 growths coming from it. Those will get roots and it shouldn't be too long. When they have 3-4 you can cut them from the old plant (right at their base) and pot them up. Wait a day or two after cutting to let the wound dry. Its kind of hard to see what is happening with the 1st one. I'd leave it alone if all the of the leads are green. Couple of other things I've noticed with your pictures. In the 1st one the plant is nice and green and looks the way it should. In the second the plant looks a little dehydrated.Think that is because the mix in the 2nd one is much coarser than the 1st. If you are watering all of your plants at the same time and they are living under the same conditions than you should try to keep them in the same mix. The lead dying out like the 2nd one is usually caused by leaving water standing in there too long. Hope that helped and sorry for being so long winded.