Tangle of Thread

I cut out a lot of fabric during the week and I'm ready to start on several blocks and doll quilts and my sewing machine isn't working. I can't get the tension right. I haven't used it in a while but it's a Viking and only nine years old so it should be going strong, plus it hasn't gotten much use so tomorrow I'll bring it over to the dealer and hope I just need an adjustment to refresh my memory because it's supposed to rain all weekend and I've got enough cut out to sew all weekend so keep your fingers crossed they don't say we'll have to send it out. Do they rent sewing machines? What do you do when you've got a handful of tangled thread...