My son broke the spool pin and I can not find a replacement. Is there a universal one that I can purchase?

The spool "pin?" Search for:

Make Model replacement parts

Sometimes you can create a replacement using a plastic drinking straw, a shortened chopstick, etc. On the other hand, there are stand-alone thread holders that can be purchased on the internet. It is usually okay to set a bobbin holder on the table behind the machine.

It doesn't sound quite right to have to remove the back cover to replace the spool pin. Most metal pins just pull out or push in, although there are some that the pin has a screw thread. But my older Berninas have a smooth metal pin. Just a thought...

Depends on your machine brand and model. Some pins simply unscrew and others pull out. Probably best to look at the replacement pin you purchased.

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Some spool pins are screwed in and some are just wedged in. You can purchase a wedge in spool pin from your local store and use it to replace a screw in one but you cannot use a screw in pin to replace a wedge in type.

It looks like it might just snap into place. Of course that means you have to remove the broken bits which may require a drill, small bit and needle nose pliers.

from the questions I read, this has happened to alot of people.
normally the spool pin should be easy to pull up with 2 fingers, if it's not then most likely there could be something wrong, you can try to use a pair of pliers to pull the spool pin up,, but if it's come loose or broke then it will have to be replaced. and some sewing machine are not mint to be opened by anyone except a factory trained technican.

Ask you local Singer dealer, be armed with the model number when you call.
Freestanding spool holders can be bought (or made.)

You may be able to (very carefully) super glue the pin back on where it broke off.

Try this site: http://www.vaccenterinc.com

or

http://www.sewingmachineparts.net/

You can search for:

Make Model parts diagram

to see what replacement parts are available.

If not, you can probably devise something to improvise. I've used plastic drinking straws as spool pins, or plastic chop sticks.