My first form check: I have been stuck on this exact stage, rather unbelievably, for somewhere between 9 and 12 months. Just about kills me every time (approx once per week as I'm trying to mix F1 course and stretching).
What seems to happen, this video suggests, is that my shoulders lean too far forwards. Hands are facing out to try and help lock my arms straight, but doesn't work 100%.
Appreciate any advice.