Many of my spools of thread have a notch cut in the rim to secure the thread. My problem is that when I use the thread on my sewing machine the thread keeps getting caught in the notch and tops the machine. What should I do? Thanks!

Try turning the spool upside down?

Use a spool cap(s) that came with your machine - you need one larger than the diameter of your spool, and the thread shouldn't get caught then. If the thread is on a stand, I agree, turn it upside down.

If you don't have access to a spool cap or turning the spool upside down doesn't work (I have a machine that doesn't like the thread coming from the "wrong" direction) you can take a piece of masking tape and tape the notch make sure that the tape is stuck to the plastic and not the thread and that is really stuck down. if it comes loose or has a spot sticking out you are defeating your purpose!

You can make your own spool cap . This will work if you are putting the spool on horizontally. It just needs to be a tiny bit bigger than the end of the spool. You can use any rigid material. I have used cardboard, template plastic , the pastic from a micro meal etc. The cap allows the thread to feed slightly upward , instead of across the end of the spool where it gets caught in that little notch. Many of the spools a few years back had the notches on both ends.
If you are feeding the thread so that the spool stands on its end ... tape the cut in the spool with a small piece of tape.

Use a nail file and file down the notch. That works the best for me if I don't have a spool cap. I won't buy thread that has the notched spool anymore just for the frustration it causes. Not worth it.

Thanks for the replies. I can't turn the spool upside down because my machine requires the thread to come from underneath the spool. I tried plastic tape and couldn't get to stick. I'll try the masking take. This is so frustrating.

I file them down too with my nail file :D:D:D

Maybe a tiny drop of super glue to fill in the notch?

The nail file did the trick. Thanks! I don't buy thread that has a notched spool anymore, but have to use what I have.