As long as the needle thread catches the bobbin thread with no big loops or tight pulls I'm good to go. All those other things are nice but they don't really matter. I love sewing on my vintage Singer and all it does is forward and reverse. If there's a problem I can usually fix it. The other day the set screw in the small belt wheel broke and fell out. A small piece of wooden skewer later and I was stitchin' up a storm!