I need to fix this as they are driving me nuts.
I've heard of opening the retractors and tightening the springs? I would suspect that the spring inside is similar to a pull start on a lawn mower just a wound up coil I'm going to take them apart tonight I think.
Pull them out all the way and spray both sides with lemon pledge and wipe with a cloth. The pledge leaves the belts slick and they will go in much faster. After a while you can repeat if nessasary. I have done this on several cars ......I need to fix this as they are driving me nuts.