I have a 2002 CLK 430 Cabriolet and the passenger door does not lock properly when using the remote or the interior door lock/unlock button. The mechanism is not totally out as it will unlock fine, but needs a little push down on the lock knob while hitting the remote or interior door lock. Is this an easy lubrication fix? I am due for a "B" Service soon and believe they are supposed to lube things like crazy on that, so any clue if that is included? I have having to visually look to see if I happened to unlock it and when using a valet, they NEVER get it locked properly! Any advice would be greatly appreciated! THANKS!