A vertical shins cue sometimes helps.
A vertical shins cue sometimes helps.
Can't really see what your knees are doing on the heavy set. The upright and plate are in the way. Looks like you're a too vertical, and the depth seems questionable. Hard to tell from the high camera angle though.
I've never used the TUBOW, so take this for what it's worth. I think you're holding your knees back too much. I don't think they're traveling too far forwards, you're just not getting them to where they need to be soon enough in your descent. As a result, they slide forward towards the bottom. Get them set by the time you're half way down. If you're using the TUBOW, think about making contact with it earlier in your descent, and then not knocking it over as you finish it. By holding them back so much for so long, you're giving them no choice but to come forward at the bottom.