It is possible that this is related to a loose bolt or nut or possibly some kind of binding in the linkage. To investigate this one, you would need to remove the screw hidden behind the door handle and the one in the arm rest. Next carefully pull the door panel up from the bottom. Be careful they are just plastic clips and normally re-usable but can be easily broken but can usually be easily replaced. Once you get the panel off, carefully peel the inner plastic sheet away from the door so you can investigate the linkage and check for any loose bolts or nuts which could result in the linkage being out of place and create a binding situation. Hopefully nothing is broken.