Another day, a lot more dirt moved.
As work continues, the "tabun" gets more and more interesting and its identification as such no longer seems certain.
The search continues for a preserved surface. So far, the best evidence for anything that can be associated with a surface is in the picture below. Shimi tells me, the white "lump" protruding from the top course of the lower wall is s surface bedding meeting the wall.
Two more days of digging to go.