I would suspect a leak SOMEWHERE. I am unsure if there are sensors on the locks or not, that would tell the pump when "all is ok". I am 700 miles from my printed copy of the service manual - but you know you can download the manual from the forum and investigate this on your own.

Problems such as this are rare - it's not an item that I, for one, am up to speed on, so I have no quick answer but 100/80 or others might.