i found a set of plastic window louvers from a spirit amx ,not sure if they are factory or aftermarket. anyway they have some small cracks in them. does anyone know a good way to repair them?
The factory accessory louvers were metal (all three versions). Most plastic louvers are made of ABS, you might try plumbing type ABS glue with some "donor" ABS material to overlap the repair for reinforcement.
After you glue them, a good vinyl rejuvenation product, something a little stronger than Armor-All should be used. Over time some of the chemicals evaporate out or are degraded making plastics brittle, and you want to add as much as possible back. I don't know what's the best product, I've just been trying things.
I have been painting old plastics to stabilize them. I wash them in hot soapy water then wipe the surface with alcohol to remove oils. I put on a good plastic primer then an appropriate paint. That seems to really help prevent future damage, and it hides repairs.