I have a Viking machine and I use Maxi Lock thread on it and my APQS long arm. I have not had a problem with either of the machines with this thread. I use other brands on my Viking as well, and they all work fine. I had one spool of variegated Isacord thread that would not work on my Viking, but that is the only one I have ever had a problem with. I have used various different spools of thread also, without a problem. I love my Viking, and it is about 16 years old. It has been a great machine. My APQS did not like Superior thread. Broke all the time.