I went out and bought a Singer Confidence Stylist 9467S off Craigslist. It was $30 and had the case and all the accessories. I have zero idea if this is a good machine, but it works and it's clean (I have bad experiences with Craigslist where everything I get from there, whether sold or free, had roaches inside them cause of the white niggers in my area).
The instruction manual was included and I used that. I've threaded it and already managed to jam my little fabric to the point the machine refused to move at all and beeps in anger at my autism. I unscrewed the metal cover thing and cleaned the jam. I also noticed it was filled with dust bunnies so I used the little brush to clean it too. I was trying to do the single line stich and it kept fraying on the bottom, and the manual said I just had to rethread the machine which helped.
The woman I purchased the machine from said she installed a "difficult to install" foot on the machine called a "walking foot". The manual claims this foot is designed for thicker fabrics so I kept it on. The clothes I want to repair are all denim pants so I thought it would be ok. Apparently the needle has to be thicker in order to see denim so I will have to buy some.
Normal jeans need a size 100/16 needle, but if it's very heavy denim you might want to look for 110/18 needles. If it's stretch denim, and not very heavy, you'll want to go with a heavy needle made for jersey or stretch fabric with a ball-point. The size of the needle will absolutely affect your stitches, if the needle is too small for the thread and the fabric you'll naturally have some puckering because the hole size is too small to accommodate the stitch. The walking foot might not be an issue because it's designed to hold multiple heavy layers of fabric for quilting usually, but if you can switch back to a normal foot you might have an easier time seeing what you're doing and controlling the fabric. If you're jamming a lot, you need to look at a couple of things:
1) is it threaded correctly through all the tension disks and hooks?
2) did you thread it with the presser foot in the up position? If you didn't, you want to rethread with the presser foot up, it releases the tension on the thread so it can lay through all the tension disks correctly.
3) how high or low are the tension settings on the machine? With that model of Singer I'm unsure if you have bobbin cases or if the bobbin just drops in to the bottom of the machine, but there is a screw on the side of the metal bobbin case that will tighten and loosen the bobbin spring that puts tension on that thread. For needle thread tension, there is usually a dial with numbers on it that shows how tightly or loosely that thread can run through the tension disks. When you load your bobbin into the bobbin case, you want the thread to pull off with light to medium resistance depending on the weight of the thread. Heavier (thicker) thread requires less tension.
4) Check your bobbin cases and bobbins for dents and such. Make sure your bobbin is wound so that the thread pulls off of it with little resistance - just pinch the bobbin with your fingers and pull a little thread out with the other hand to make sure that it comes out freely but not completely free. You want the bobbin to hold the thread but not grab it, if that makes sense. If the bobbin was wound funky, try to rewind onto a different bobbin or at worst case, cut it all off/pull it off and start again with fresh thread from the spool.
5)
Check your stitch length before you mess with tension settings. If your stitches are way too tiny for your heavy fabric, that will cause jams and snags. Find a piece of scrap light cotton fabric (a bedsheet or a pillowcase works great for this), make sure it's folded double, and run a few lines of stitches with it on like a 2mm stitch length with the thread you're using for the jeans - if these look even without the bobbin thread showing through and no puckers, your problem was likely stitch length rather than the machine tension. If your stitches are still puckering/snagging/showing bobbin thread, then you definitely have a tension issue and you'll want to adjust the dial. You want looser for heavier thread (but not too loose) and tighter for very thin or slippery thread. Your stitch length for heavy fabric should be longer rather than shorter. 3mm is usually pretty good for jeans.
I personally don't have a lot of experience with a walking foot, so maybe some of the quiltfags here can pipe up and offer some help with that. I did look up your machine and it looks like it's a very basic machine but I have no experience with it so I'm really glad you've got the user manual because that's what's going to save you. Before you start just trying to mend things go get some old jeans that you can cut apart and that way you can set up your stitch length and tension with scrap fabric and then practice! Seriously, best of luck, just be patient and read your manual!
