I have looked at the tightness of the feed dog, although I can not make it any tighter but there is a little movement there.
I hear you on the 'reverse',
Just so you know the other day I had a sample of 22mm of the hardest sole leather stitched together (4 layers), reliably, it was stitched on a BLAKE DN76 machine, that's the kind of machine I should have bought.
take care