door actuator

Hi, I've got a polo 9n, fabia / Ibiza chasis etc,

The drivers door won't always unlock on the remote while the passengers and boot so, but will open with the key, I'm thinking the actuator is on its way out, its not consistent and hapens may be once or twice before opening on the remote again for a while before playing up again, but is there anything else to check before drilling all the rivits from the door guard?

Thanks

Dan