I bought a little Vivitar V3800N at a yard sale a while back for $5 mostly because the little battery cover was missing (and the owner wasn't even sure film could still be developed.) This is not exactly a camera that gets a lot of praise but it works just fine. 4 years later the cover is still missing and the camera is still going strong. I am sure it is psychological but I can go through roll after roll in this camera without getting all sweaty about it. I don't talk about it much but every year it is one of my most used cameras.
Great pictures as well.
Maybe your Yashica Mat will turn out the same for you. Sometimes knowing that the camera is not perfect allows you to look at it a little different then one where everything works. Shove a cotton ball where the battery goes, tape over it with a piece of gaffers tape and go shoot film.