electronic parts

[leon]

I have a power pack which I built long ago and now having a problem with it. I trouble shooted it and found out where I am in need of a potentiometer. Radio Shack doesn't have one and I am at a loss as to where I could find one. It is a 250 Ohm NPN pot. If someone knows any electronics hobby stores where I might bye one, please let me know.

thanks; leon