I have 3 problems - one I solved by looking through other peoples stuff which is the shotage f green and pink keys - I'm not asure that I quite buy that you only get 1 to use for each pair of door but so be it. 

There is a whole area behind a grey door in 16513 that I cannot access.  I have tried everything and feel that the area beneath with multiple levers and steps must hold a key if you can climb up the chain but for me, there is ne step missing!

Also, there is a red key in room 16117 which I can't get to!  I have tried climbing the vine on the page to the right and have died numerous times as a consequence though it seem to me that this vine has no actual function.  I can't crawl along from the left.  I have tried climbing the vine underneath for which you cannot see a cap which usually means that it disappears behind the wall but I have tried pushing everything and pulling levers and no, I can't climb up it though for the life of me, I cannot see what the lever on the right over the stream actually does.

Please help - I can go on trying just so many times and now would like to move on.

I've tried to get to the door from the otherside.  Clearly you can open it from behind but I cannot find a way into the room to the right of it.  I feel that you should be able to climb the chain that had a key by moving all the steps but I cannot see how.  The room above has the boxes in it but I cannot find a away to go down.  Can someone please confirm that you can get into this room and from what direction.

As for the other red key that you can see, I have investigated this room from every angle until I have died numerous times!

Can someone give a a hint?