final drive seal replacement

[DAK]

Help, I've screwed something up! I'm replacing the final drive seals on
the transmission. I did the passenger side yesterday, no leaks visible.
I did the driver's side today, leaks! Is there something special about
this side? Do I need more than gear lube when putting it in? I got it
pressed in, past the chamfer, then proceeded to drive it home. It did
get a little off, but I got it straight again. Should it go all the way
into that shoulder? Does the passenger side differ from the driver's
side? I know the seals are the same, but do the go in different amounts?
I had another seal (that was supposed to go in the rear) and tried that
one. I tried to be very careful about keeping it straight. That leaked
also! It is possible that I didn't get enough lubrication on the seal
before installing it?
I'd done passenger side seals before, once on the 5KTQ and once 4 years
ago on this car. While I could have messed it up, I find it hard to
believe that I could install these others right the first time, then
mess this one up twice in a row!

Any ideas?

Thanks,
David