My grandfather was with the 1st Battalion, in the same vicinity (Broodseinde), and was wounded the same day as you great uncle (4/10/1917), the first day of 3rd Battle for Ypres. Luckily(?), he was wounded in the legs by German machine gun fire, and survived the War.
From my research the Jabber Track was a series of wooden duck boards which were layed across the mud, so soldiers could walk without getting stuck in the mud - it wasn't a track as such. In my records I researched on my grandfather, I have a photo from a book captioned "Fifth Division soldiers on the Jabber Track in the Passchendaele area c.November 1917".
My research notes on my grandfather's indicate ".......... 2.30am 4 October, 1917, soldiers of the 1st Battaltion moved from their position at Westhoek by walking in a single file on duck boards along the Jabber Track, reaching their assembly point at 4am. At 5am the 1st Battalion was finally in position some 1000 yards south of the village of Broodseinde itself. The 6th Battalion was on its left and the 4th Battalion was on its right. Zero hour for the attack had been set at 6am". "
I obtained most of my research notes from the Battalion Books, which are written accounts of individual Battalion's war history. Unfortunately, not all Battalions have a book, but the 1st Battalion does. These books are available, but you have to find them.
Les
Les
