SL 129 Door wont open from the inside

[marcmulcahy]

I was hoping someone could help us with this ?
A friend has just bought a beautiful SL 129 series and I am trying to help him with a few teething issues.
The SL 280 (129) has a problem opening the drivers door from the inside.
Basically both doors lock automatically as you drive off.
If you pull the chrome lever on the passengers door, the lock button lifts and the door opens.
If however you repeat the process with the drivers door you can see the lock button move ever so slightly but the door remains locked.
You have to press the button on the dash to unlock it then the chrome lever releases the latch.
Everything works perfectly with the central locking, exterior door handles, remotes etc....
I would be really grateful for some advice with this.
Thank you.