Q.Christmas cactus
My old plant has a section that is turning woody at the base and the leaves are yellowing and wilting. The plant was repotted last summer and another larger shout broke off at that time too. What can I do if anything to keep it alive.
The base of a Christmas Cactus turning woody is not generally a negative, but actually means the plant has been doing well and is just aging.
Yellowing leaves however can indicate a watering issue; either too much or too little. You should also check for pests or other signs of disease.
These links have more information for you.
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/woody-christmas-cactus.htm
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/yellow-christmas-cactus-leaves.htm