Timing chain tension to rear cylinder head

Hi I was changing the gasket of the rear timing chain tensioner, the Spring loaded one between the heads, I took the cam cover off and marked the cam positions etc. The tensioner can out easy enough but I've hit a snag I can't get it to go back into the head. I tried it without the spring and piston just to offer it up and it will not go into position on, does anyone know how these go back in?

Thanks

 

thanks fingers crossed it goes back, I will try again Thursday thanks for the photo links, has anyone got photos of timing chain with cover off as I would like to visualise what I'm dealing with

 

This is a huge thank you for all the great help and advice. When that tensioner resolutely refused to go back into the engine I must admit to a certain amount of swearing, followed by talking nicely to it then despair. The advice you all gave and the pictures were spot on the tensioner had gone out of line from the hole. I used a stiff wire and made a hook and after a bit of fishing I hook the tensioner and managed to line it up and it went in.
I found the push rod/ Spring when all the way compressed wouldn't engage with the tube so I allowed a small amount to project out the tried again and it went in. Loud cheering and I think I shed a tear as well just the relief of it going back on.
So this is to say Thank you to everyone.
That assembly when it compressed off the car feels like holding a grenade I must admit to having great respect for it and keeping it in a metal container until I was ready to offer it up.

I'm so glad it's back on Thank you again