5th door knob sticks

[komichal]

Hi all,
Whenever I tried to open the 5th door of my 2007 Yaris by pushing the metal button, the button stayed pushed in and I had to hit the black handle so that the button pops out back.

This one:


I tried to spray WD40 around the button, it helped a bit. I also popped out the small cover from inner side of the door a sprayed a bit of WD40 on the moving parts. It helped a bit as well but it is nowhere as good as it was long time ago.

I know that WD40 is not a solution to all world problems, I just wanted to check if little grease is all it needs... and I am not convinced now.

Anyone experienced the same? Is there any tired/worn out part that needs to get replaced?

Or do you think I should really take the mechanism out, clean it up properly, re-lubricate and it should solve the problem? If so, can you please kindly advise how to remove the interior plastic panel from the fifth door? The small hole in it with pop-out cover is more for emergency opening to be performed by a skilled gynecologist, but definitely not for doing proper maintenance.

Thank you all.