Update: There is this particular workshop at Kaki Bukit, "Elite Car Ventures". They provide a very in depth explanation about the possible issues with sliding doors. Although this portion of their explanation falls under the category of Vans, I believe they have the expertise to deal with your sticky situation as well. A quick google search online shows that they do a myriad of other vehicles apart from Vans, and has very good reviews online as well. Perhaps you can consider contacting them. Hope this helps.