Offside rear goes down but self levelling don't go down with it.Why?

I am new to the forum but would be so pleased to get an idea about what to do ? I bought an
air bag for the rear offside but I have not replaced the old one as I can not hear any air leaking out . Sometimes it does not go down overnight especially if I park with the rear nearside up on the pavement. What I need is an explanation as to what is going on. It is possible to drive the car after it pumps up the offside , but now it can "Bottom " with a bang and I pumped up the airbag by using the Offroad setting in the emergency while still moving.
By way of introduction I live just west of Oxford . This is my first LandRover and the engine works a treat . But the suspension is a worry. I know more about prewar cars . My first was a 1927 grand prix type Amilcar, similar to a type 35 Bugatti but not as well engineered . Like
NO Differential. Interesting when cornering . Be interested in any views on the above problem . Thank you

First of all you need to ask this question in the right place and when doing so give details of what model Land Rover you are talking about.

Welcome

Your question/problem is very common it’s a matter of working through and tracking the leak. Bags best replaced in pairs as they will both be as worn. And often parking and different levels like up on a pavement will fold the bag different and so may cover the leak. Don’t leave it too long or you will be needing a compressor too.

But best thing to do right now is read through this info first

https://www.landyzone.co.uk/land-rover/checking-eas-compressor-and-diaphragm-valve.172555/

Then ask about your problem in here.

https://www.landyzone.co.uk/forum/land-rover-discovery.8/

The gurus will get you through it

Enjoy.

J

Edit just looked and you have a disco so the first link maybe irrelevant although some similarities I am sure.

Welcome to the forum