Not sure how "technical" this is but I'm wondering if anyone has an idea for a fix for this. I lost one of the two tabs (circled in the picture) that secure the vent flap for when you are driving. I can't find anything online that allows you to buy just a new plastic deal. The new vent assembly is only $12 but than I'm looking a more involved replacement project.
My theory was to fashion something to go on the bottom of the flap. Similar setup as the side vent tabs but larger and easier to access. Maybe just screw it into the bottom of the plastic assembly?
Go to your closest hardware store and ask to see their plastic (may say nylon on package) "screen clips". Buy the ones best suited for your needs. I know stores like Ace and Lowe's have an assortment of them. The cost is negligible.