I don't know about your machine, but I have a Baby Lock that has specific instructions in the manual to not adjust the bobbin tension on the special bobbin case. I think that's unusual, however, and I have made that very slight adjustment on a few machines. It never seems to help me, however. Sometimes what looks like a problem with the lower tension is actually caused by the thread not getting engaged properly in the upper tension. Sometimes there's some thread or fuzz caught in it. Try rethreading, and always cut the upper thread at the top and pull the piece out from below. You may need to take the machine to a shop to clean out the upper tension area, which - if that's all it needs - is not a very costly or time consuming fix. I hate that the tension disks are in where we can't see or reach them on modern machines.