Lost reverse, need help finding it. 727

Trailbeast have you installed one of the super servos?
I can't seem to get the seal to slide past the retaining ring groove. Without the seal it slides right in.
I don't see how its even going to slide in with the stabilizing ring on it.
Any suggestions?
First I tried living it with transmission fluid, then I tried petolum jelly, as stated in one of the rebuild videos.

Freezing it is a good trick. I have also used a very thin feeler gauge to fold the seal down as I push the servo in. Slide the feeler around the bore as you give it a little pressure.