1977 450SL steering box

[das5150]

Ok... I think I know the answer here, but am hoping I will be pleasantly surprised.
The box is completely dry and working fine, except for a substantial leak at the steering shaft seal on top. No excessive play or any issues, just the leak at the top.
I have my full seal kit here on the branch, ready to go. The top bearing cap and all that came off very nicely. Now.... The big question:
Do I just do the bearing cap o-ring and input seal, or do I tackle the whole reseal job? Is it coming out of the top because of excessive pressure below, or should doing just the top seal fix it?
I know you are all going to say: you have it out already, do it all! But I really don't have time. Sure would be nice to press this seal in and be done.