Needle position won't hange

The instruction manual (https://www.manualslib.com/products/Janome-Myexcel-23x-Mx3123-3787947.html) page 23, "Infinite needle position," has one likely answer - you can shift the needle from center towards the left using the infinite needle position control. This can be used to center a zig-zag stitch in the presser foot - just move the needle position half the distance of the stitch width.

give a gentle pull and get it into position, could have gotten stuck by accident, also put a piece of fabric under the needle and press on the foot pedal to make the machine "go". It should begin moving the needle bar and straighten up.

When the needle is set on the center position, is it centered or is it slightly off center? If so, then the mechanism needs to be adjusted so that the needle is perfectly centered. When it is off-center, you will get the problem you are experiencing with hitting one side of the zipper foot. May want to take it in for service.

Don't know about your particular model, but maybe left is the normal "resting" position. When on zigzag it will move to the right then back to the left. As long as all of your different stitch patterns keep the needle between the limits of the hole above the shuttle and does not hit the machine bed then I would best guess everything is fine.
Hope that is of some help.

set the machine to straight stitching which should keep the needle in the center position
a zipper foot is a normal foot with 1/2 missing
It it still wanders , take it in for a service

check that the settings mode is for straight sewing and not some fancy stitch

According to this manual (pg 52):

http://www.searspartsdirect.com/partsdirect/user-manuals/3116-SINGER-SEWING%20MACHINE-manual

the zipper foot position is adjustable, not the needle position.

go to the website of sewvacdoctor.com & email them the question

Hello,
Here are some solutions to try.

* When you insert your new needle, make sure it’s positioned correctly (usually with the flat side away from the bobbin, but consult your manual), that it goes all the way into the holder, and that the screw is securely tightened.


If there doesn’t seem to be a problem with your needle, try the following:

* Check your pressure foot and make sure it’s attached securely.


* Change your pressure foot Your pressure foot may be bent, causing your needle to hit it.


* Don’t sew over pins a needle that hits a pin can break. Always remove the pins from your fabric before they reach your needle.


* Don’t pull your fabric as you sew. You could be bending your needle back, causing it to hit your needle plate instead of going into the hole. Just guide your fabric, letting it feed on its own.


* Check your needle plate and make sure it's securely in position.


* Change your needle plate. If you’ve been using a straight stitch needle plate (a plate with a small hole, often used for sewing fine, delicate fabrics), switch to a needle plate with a wider hole.


* Check the position of your needle. Sewing machines with zigzag capability allow you to adjust the position of your needle – right, left, or center. If your needle is not positioned correctly, it may be hitting your needle plate or pressure foot.

Hope this helps.

perhaps the needle is not in straight or is bent.