Having a problem getting over the crack? Let me help.
First of all, sprinting past the sentries is not the way to go. This doesn't always work, and getting over the crack in the window works 100% of the time although sometimes it takes about 20-30 seconds.
So, you get to the crack and you basically just keep pressing jump over and over (speed pressing it). Once you jump up and get on the platform you need to immediately jump again to fully get over. Sometimes I get this on the very first time I do it, sometimes it takes about 30 seconds or so. But the point being is that it always works. No need to bother with sentries at all.
Keep trying and it will work for you.
- H