Friction shoe part # 15-104

Greetings. To remove and install a new friction shoe, you will need to remove the sashes and the jamb liners, then slide the friction shoes out of the jamb tracks. Taking apart the window is no easy feat and varies from window to window; you may want to contact a local pro to do the job for you. 

There is one alternative option, but it comes with risk that you will damage your window. In theory you can heat the track up a bit so you can squeeze the new shoe in. With a heat gun or hair dryer, heat up the track near where the old shoe is sitting. When the track is soft enough you will be able to remove the old shoe and install the new one. If you choose this method, be extremely careful not to over heat and damage the track. If you damage the track, your window will no longer function.

Let me know if you have any other questions.