I have a used HQ16 and love it. Haven't had a problem in the 2+ years I've used it - aside from operator error!
DH took it apart after 2 years to clean it for me. It was amazingly clean inside. It really didn't need cleaning - except that there was a piece of thread caught in the 'needle up and down' mechanism. It hadn't given me trouble, but probably would have in the near future.