1996 Range Rover Suspension Issues

Hi all im a little new to all this.

im experiancing air suspension issues with my 4.6hse range rover. hence im hoping i can get some help from here to repair the problem or at least diagnose it.

i'll try to explain, if i leave the car in the normal road setting the suspension levels to the bump stops and then takes ages to come up some time whacking it over a bump does help to settle things and get it to come up. it always appears to be the rear that takes the time or goes down 1st. however if i park the car (even over night) with it pumped right up it stays up and i can drive away.

once it has been up some times and i mean some times it will go up and down quickly normaly every time i start trying to trace the fault which dont help me!!

ive have the compresser running with out the filter so theres no restriction but that dont help. tried tapping the valves to see if one is stuck but cant see how that would work as if it was the valve surely it would fail on just that one corner?

so help and advise please its a horrid ride with out it.

First place to start is with a leak test
Arm yourself with a spray bottle full of soapy water and check all springs, pipes and the valve block for bubbles
Do your rear bags look perished/cracked ? - if so, dont **** about get them changed it's not an expensive job to DIY so no excuses
My money would be on a rear air bag leak
In the meantime, dont "whack it over a bump " to get the suspension to come up - you are asking for a hard fault and a trip to the dealers to reset
Start it up in the morning and leave it running with the front door cracked open - then go for a coffee or a **** for 5 mins
When you jump in and shut the door you may need to remind the system what it is meant to do by pressing thee normal height button on the dash but up it will come