A vintage machine would have to be abused quite badly to throw off the timing. I believe one would see, at a minimum, lots of needle strikes on the needle/stitch plate.
When I get a machine, I clean and oil, but don't touch the tension at all, until after I see how it stitches. I'll adjust the tension if needed, but don't remove it to deep clean/polish -yet. Checking in this manner separates the machine capability from user error.