Is it me or is it near impossible to zoom in on the end of a sample?
I’m control clicking and zooming but it’s hard - a lot of scrolling and unintentional zooming.
In fact setting the end point of a loop - I’m looking for zero crossing points - is challenging.
Indeed that is challenging and there is room for improvement there 
What I suggest that you do is click close to the point you want and repeatedly press the + button. That should take you almost there. Try the rest with the mouse.
i will also put a zero crossing snap option on the feature request list, good point.
Thing is if you click close to the end point you lose the start point!
dang, sorry, good point. That functionality was made with the idea of zooming in around the start point, but not for the loop-end point.