Drivers Door Lock

When I put the key in, it turns and the pull up on the inside moves slightly but doesn't unlock, so I have disconnected the battery (alarm was annoying wife and neighbours!!) and gone in through the passenger door, it wouldn't pull up on it's own but a pair of grips and it popped up!!

Just wondered if anyone had any ideas before I start taking the door card off as my mechanical skills are very limited!!

could just a bit of lube required, but it could be an iffy lock spring there's a bit more work with that one, u will only find out with the door card removed

Cheers, I'll get the door card off then and squirt some WD40 and then post an update!!