Warning: if your carpet ripples after 6 months, check your tackstrip first, not your stretcher
Did a warranty callback in Boise last week, Berber in a hallway that had waves in it after only 5 months. The homeowner blamed the install, but when I pulled the edge back the tackstrip was cheap 3-ply with pins that folded over flat. Swapped it for real 1.5 inch strip from a different supplier and re-stretched the whole run in about 40 minutes. The difference is night and day, tight as a drum now. Anyone else seeing junk strip come through their supplier lately, or is it just who I've been buying from?