I just had the same problem with my 722.3. I got the only tech at the dealer who knew what he was doing on these units to rebuild it ($3,400). Don't know if the 722.5 is the same, but the clutches on my reverse pack were worn out and there was also a tear in one of the seals that made the "slow to engage in reverse" problem a "does not reverse at all on a slope" problem. He said that this was exactly what he expected to see when he tore it down--no surprises. The forward clutches were fine. Check out S-Class's post if you intend to fix it yourself. http://www.peachparts.com/shopforum/showthread.php?t=193317&highlight=cover+guys
Good luck.

__________________
1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles