I've just bought my E61 LCI (2007). The rear glass switch wasn't working when I viewed it but dealer (non BMW) fixed it before I collected it (wiring issue).

My problem is the tail gate seems really heavy and the gas springs won't lift it. I've seen all the threads about gas sprigs and I've got new gas springs waiting to be collected, but I can't help but thing the problem is at least partly in the hinge.

The glass panel itself seems quite heavy to open, way more so than on my old E46. It needs to be physically lifted and it doesn't feel like there is much in the way of spring assistance. With the glass panel already open fully the tailgate will lift itself on its gas springs most of the way, and then slows right down for the last part of the travel. With the glass panel closed the tail gate will not lift its self at all.

Is this just the main gas springs or is there a problem with the hinge? If it is the hinge then what do I need to do (can't see the actual pivot point? Car is generally in very good condition otherwise.

 

Mine is stiff and needs lifting when it is cold but is fine and lifts under its own steam when warmer

 

I recently replaced the gas springs as well, no more pushing required or heaviness of the main tailgate. Indeed the last part of travel was hardest and we bumped our heads often. Now with the new ones it pushes right up to the top, works great.
I would guess your whole issue is weakness in the old gas springs as well. As for the glass panel: if it's down, there is probably more force required to open the tailgate. (Weight of the panel + leverage) So I am hopeful the new springs will fix the entire problem...

 

New struts fixed it. Looks like only one had gone but replaced the pair.