Balance won't stay in window

The small clear plastic endcap that attaches to the window has broken. The balance will not stay inside of the window unit because the endcap is broken. I have been able to identify the balance part number 2730 0. I'm not sure how to get the window out of the frame to be able to remove the small broken plastic piece and replace it. I provided a photo of the right side of the window where the endcap is not broken and a photo of the left side of the window where the endcap is broken. Any help identifying the clear plastic part as well as replacing it is greatly appreciated. Thank you.