Before you mess with the tension, use a different color of thread in the bobbin and the spool of thread and a new needle to see just how the tension is working on your machine. It might be OK. If not, watch Muv's videos and go from there.
I keep a small spool of thread, a bobbin of other thread (I can always transfer it to the one with the machine) a scrap of fabric, new machine needles, and a tiny pair of scissors in my purse, just in case... I come across a vintage machine I want to try out. I did that with the last Singer 99 I bought, much to the amusement of the clerks in the store. It let me know just what I was getting.
That little oil can with your machine is so cute, a real keeper!! ")