Head job not going well...

Just got a valve job on my head. Re-installing the head is challenging.

Removing the upper timing chain gear was relatively easy. The opposite is not true.

I did not have or need the special tool for removing the chain tensioner. I was able to remove the cap and spring and the chain and timing gear slipped right off the camshaft. Upon reinstalling it, I now see that the tensioner pushrod won't go all the way backwards into its recess.

Is there any tip or trick to re-seat the tensioner pushrod without removing the whole chain tensioner?? Please say yes...

If not, is there another tool that'll take out the tensioner?? That internal 12(?) point retaining ring looks like about 18mm...

I am totally stuck without help...

And one other thing: While monkeying with the whole thing, I broke the driver's side chain guide... (Plastic) How critical is this? Replacement requires pulling out everything on the front of the engine including the harmonic balancer and as I read it, the oil pan!

Many Thanks!