[MEvang]

This does not surprise me, seems that once these seal start to leak it hard to get them resealed. This is of no fault but the technicians doing the job. If your sloppy and careless it will leak again. This is why, with a little instruction, you are better off doing it yourself. I find that a unskilled owner if many more times observant and careful then a tech that's in a big hurry to get it out of his bay.
Here is some rules for a successfully seal install:
1) Don't damage the seal. There are proper tool to install a seal but if your very careful you can makeshift something. Just make sure its in square and has not been distorted. If your in doubt, get another seal. This is the cheapest part of this job.
2) Using a little sealer around the outside of the seal won't hurt. Matter of fact I recommended it.
3) Lubricate the seal. This is almost always skipped and the seal burns up in a few miles. Use a little white grease on the seal lip and axle.
4) Make sure there is no damage to the surface of the axle that the seal rides on. If there are some minor nicks or scratches use some emery cloth and clean it up. If real bad replace the axle.
5) Be careful not to nick the seal when you slide the axle back in. Most seals that leak right away are damaged when the axle is installed.
One last thing, take the time to completely clean up all the mess. Grease you leave behind can make you think you have a leak latter when you don't.
Follow these rules and you can't go wrong.
Mike