Channel balance for a single hung window.

One of the channel balances of a single hung window in my diming room was broken as shown in uploaded pictures. The stamp number is 30 C. The other two pictures show the placstic ends on the metal channel. The width and the depth of the metal channel are all 9/16". The length is 32" including both plactic ends or 31" excluding the ends. The window itself is a 32-1/2" X 38-1/4" double pane wood frame window. There is also a broken plastic block 13/16"x5/8"x9/16" which is mounted on the sash to hole the sash on the metal channel. I am looking for replacement for these two parts. Let me know if you need more information. Thanks