They are likely on their way out. When I bought my 86 GN with 9000 miles at auction last year, the bumper fillers were shining perfectly except for the front passenger side. I figured I would just have it painted. When I got the car home, I noticed that the driver's side was starting to haze over. A few days later, the rear fillers started to haze. When you rub the fillers, they shine up for a short period of time and then haze back over. Apparently, the prior owner must have buffed the heck out of them right before the auction. I then took the car to a body shop to have all the fillers repainted thinking that they were just fading from age. Unfortunately, after paying $700 to have them painted, a few months later they hazed over again. I can rub them and shine them up but they soon return back to a haze. As such, my assumption is that there is some degredation going on with the fillers from age. Sure enough, the front driver's side recently cracked even though it felt soft and pliable. The car has been in my car for months. Just cracked on its own. Consequently, I wasted $700. I have purchased a new NOS front and rear set for a pretty penny (especially the rears) and will again be paying to have them all painted. I also notice that alot of the low mileage/original paint cars you see advertised online have faded bumper fillers. You have to look close in the pictures but you can see the fading/hazing if you look at the pictures closely. If yours are hazing and can be shined up by rubbing them only to soon return to a haze, in my opinion, do yourself a favor and get new fillers. New paint will only last a few months and you'll be back to sqaure one.