Sash Guide

Have a broken Sash Guide. Ordered (2) 18-161 guides yesterday. I was only able to get 2 measurements-5/8" & 7/8". Tried to remove window to measure the length of the sash guide but was not able to do so.

Ques. #1- should I see the aluminum channel (IMG 0640) if the sash guide hadn't broken? Do I have to slide the Aluminum channel down to be able to remove the window? I have 6 identical windows. I can't see the aluminum channel on 4 of them that work fine and that I can open. I can't see the channel on another window, however, that window is not accessible so I can't determine if the sash guide is broken on that window.

Ques. #2- is there a tutorial on removing window? Attempts failed. Mfg. code on window is ALC-1. DH-R40. MST 4665 ser 437/438. ALCAN is stamped on the windows.

Thanks for any any assistance you can provide me with.