I have a 60" Mira, a little newer than yours. Probably made 70's? or later? I don't really know. But I have experienced some difficulty getting a good shed when I tighten the warp nice and tight like I do on my Tokia countermarch loom. I have to keep the warp a little loose, or I cant treadle the shafts for a good shed. The downside to a looser warp is the increased risk of a skipped thread. I bought my used Mira to make double wide blankets. I have only sampled in cotton so far. My project next will be a double wide wool blanket in the next week or 2. Frustratingly to me, is I cant manage the full 60" without the flying shuttle. But the flying shuttle is in itself problematic with skipped threads, so I took it off. Now I've sampled at 50" and it's doable free handed. But I cant tighten the warp as much as I'd like and risk the shuttle diving down through the warp. When I first put this 4/8 cotton warp on the loom I didn't notice the need for a loose warp. It seemed to develop as I wove along. But I cant see any issues along the way. One thing the flying shuttle provided was a nice shuttle race along the beater, but now without the flying shuttle on the loom there is much less of a race, so I might have to adapt a plastic ledge to make a shelf, for weaving safety. When the warp is tight, I cant get the warp to settle down onto the bottom of the beater. Good idea to go to Ravelry. There is also a FB group for LeClerc looms.