Hi, I've been getting into tanning more, for sheep and goat rugs mostly. I'm having trouble getting them flat, especially the rump area. I only use a couple of hand tools, and I've used a number of tanning chemicals but keep coming back to Trubond 1000b I've pegged them out after tanning and taken them down just as they are drying to break them. They break fine, but the lump over the rump comes back after breaking, leaving the hide lumpy on the floor. What's the trick with that?