steering box rebuild - trick to getting power piston back into the box?

So I'm finally getting around to reassembling my durango box and I can't for the life of me seem to get the power piston back into the steering box. Following the saginaw rebuild thread on pirate I installed the worm gear (and input assembly) and now the power piston just won't go in.

The piston slides in fine w/o the teflon o-ring but once I install the [white] o-ring it gets stuck at that ring. I do see that the inside of the box itself is tapered a bit which seems like it would help direct the o-ring in but it just won't go.

I already tried brute forcing the piston in once and destroyed one teflon o-ring (and had to order a 2nd rebuild kit) so I figure this time I'll try and fineness it in there if there's any way to do so. Anyone else run into this problem and have some advice? :dunno:

Disregard this question, figured it out myself.

For anyone else who may find this thread with the same problem: I ended up fixing this by letting the piston slide in as much as it could until the o-ring was butted up against the box housing. Once it got that far I kept a bit of pressure on the piston while I ran the back edge of a knife around the piston (between the o-ring and the steering box housing) in order to make sure the o-ring was fully seated in the groove. Once I did that I carefully gave the piston a few taps with a mallet/hammer and it slid right in.

A good write-up to help for future searching:
http://www.pirate4x4.com/forum/showthread.php?t=570869