Silvretta Pure Performance binding flaw

I own the Silvretta Pure Performance binding and have many problems with the heel risers. I have already gone through two heel lifts, they have cracked right off as I try to lift the riser up one level, or the thin plastic just splits and the part no longer is functional. I believe this is an inherant flaw in these bindings. My bindings are from 2005, the newer, updated model now have a beefer plastic heel lift.

Anyone experiencing problems like this with these bindings? I love them otherwise but I fear getting stranded in the backcountry, far from the road, with a busted binding.

Are these AT bindings? You'll have better luck asking on a ski specific site. Someone on telemarktips might know something, but then again, they are almost all just tele fanatics who don't use or like AT gear.