I use 3M VHB [very high bond] trim tape.You need to remove the entire guard.Remove all traces of the old double sided tape and also remove all traces of glue and wax where the moulding attaches to the car.Both surfaces must be wax and oil free.Also don't do this on a cold day.Wait until spring.The product works great.Be carefull when you peel the trim away from the car.The moulding has 2 centering plugs that you do not want to snap off.I removed all of the guards from my 89 240 before having the car painted.I also painted all of the guards with SEM flat black trim paint before applying the 3M and mounting them on the car.I would avoid washing the car for at least 2 weeks.