I've documented my assembly process in my blog. https://blog.cyril.by/en/3d-printers/sapphireplus-assembling-tips

For the filament run-out detector, you'll need to print a piece in plastic that'll be mounted in one of the column so it's not hanging on the filament itself (which, as you've noticed, will likely cause issues when unwiding the filament). I had a lot of issues about this detector, mine wasn't wired correctly. Feel free to comment on my post, so I can include your experience on my page, it might help others. Thanks!