So I have this 1959 Bus and the sliding windows are Sigla but they have a metal channel on the bottom and no holes for the window latches. The latches evidently attach to a horizontal lip. The windows don't move because they were installed with the felt channel on the bottom and the windows my guess is that only the glass without the metal channel needs the felt and mine do not and the metal slides over the metal channel. I am wondering if these windows were original to this Bus and where I can find latches for it anyway. The only ones I have seen go through the glass. I thought all Sigla sliders were like that. What gives? James