Thanks Steve for your help. that is what I have done but I seems to have hard time pulling the bobbin thread into the middle of 6-7 oz. leather. I'm thinking I will put a smaller size in the bobbin and play with the tension on top to solve that problem. I replaced the tensioner unit on top because the old ones was broken in a few places but this new one seems maybe not give me the proper tension that I think I need, not sure. I was told by the store I purchased it that if I was to file a tiny bit off the little pin that are inside the tensioners hollow bar, that the tension disks slide onto that this would increase my tension. I'll play now that I know what my max. needle and thread are and once again thanks for your help.
Darryl