I have a white 955 can the spool holder to replaced, mine broke off

hi harriett.
go to this link should help you to get one.
spool holder for brother sewing machine Google Search

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.

Check the local sewing repair shop to see if they can order it for you. You can also search the internet for the manufacturer, model and the word "parts" to see if there are any online suppliers for your machine. If you are creative, you may be able to jerryrig something using a plastic drinking straw, chopstick, or a wooden dowel.

...

try this site for the part

http://www.sewingpartsonline.com/white-1740-sewing-machine-parts.aspx

here is a link, see if any of these parts will help

http://www.sewingpartsonline.com/pfaff-955-serger-machine-parts.aspx

I've check different sites for one & can't find any, here's what I
suggest, check with a sewing machine shop in your town & see
if they can order one
or email these sites about one, give the name & model number
of the machine
sewvacdoctor.com
a1sewingmachines.com

try the singer website or sewingpartsonline.com

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

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

or

http://www.sewingmachineparts.net/