Door lock sticking

[joko]

when it is unlocked, my car door lock locks itself down whenever I pull the inside lever.

I have to hold it up with one hand while i pull the lever in order to get out of the car.

it has only just started doing this, but in the past it would occasionally stick when using the key and i'd have to open the back door and reach inside to push the lock up

any ideas whats wrong, and is it something i can deal with myself?

Thanks

(its a peugeot 405 auto estate, 12, 1995)

[NORMANTHEDOG]

try a good dose of WD40 on it.