Were you stitching woven fabric or a knit?

I have a problem with knits and this is an idea I will try next time.

Question..........when you said it would cease zig-zag stitching, did the ram actually stop moving side to side? Or did just a few stitches go straight even after the ram moved side to side.

I think needles "aren't like they used to be" & the quality is less. So it might've been a poor quality of needle?

Good that it was an easy fix & nothing wrong with your machine!

Calliope, I kept trying to watch it carefully and it appeared that it was always going side to side, yet the stitches were straight in some places. Weird. Yes I'm glad it stopped with a new needle, but I'm just curious why this happened. I looked at the needle and couldn't see anything wrong with it.

I used to do commercial sewing and I can tell you a needle can come right out of the box (new) bent. Also your machine can "like" the needle turned a hair one way or the other and won't sew any other way, or it SHOULD like the needle straight and if you turn it a wee bit it will throw everything out. Also a piece of fuzz or lint or dirt or darn near anything will cause a machine to not perform correctly. First thing I do is change the needle when I got something going haywire. Just my two cents.

I agree ~ needles are often the culprit of poor stitching and the microscopic pieces of lint and dust. The eye of the needle is often an overlooked area of the needle. A burr, or slight imperfection will cause inconsistent stitching.
I buy good needles - I like Schmetz brand. I try to always use the correct type and size, and I change my needles often.
A good practice is to always cut the thread above the needle and pull the thread out in the same direction (as if stitching).

Like nbgramma, when a stitches are a problem, the first thing I do is change the needle and retread from the beginning of the spool to the needle.
Glad it was a simple fix.

"it appeared that it was always going side to side, yet the stitches were straight in some places."

Well, that makes sense and I was hoping you'd say that. There is an orchestration under the plate in the bobbin chase where a loop of bobbin thread wraps around the thread brought down into the fabric by the needle. If everything isn't exactly in the right place, at the right time, there won't be the locking of the stitch taking place. If you are zig-zagging, it will appear as a straight line of thread between zig-zags and means a complete stitch hasn't been accomplished. Yes, an incorrect needle position, even a hair off.......or timing can do this.

Same here....any stitching problems I have always seem to involve the needle. Change the needle and problem solved. Sometimes those needles are not "perfect" even brand new out of the package, and/or a nano speck of lint, fuzz, or the wind blowing the wrong way will throw it out of whack. LOL
I once had to do TWO needle changes to fix my issue, nearly went nuts that time. Because TWO bad needles in a row??? and they were Schmetz.
So glad it was the needle and not your machine.
Happy Stitching,
Murphy