No kit as far as I'm aware. It's been many years since I did this job years ago, but if leakage is the only issue, carefully take it apart and match the o-ring sizes to very close regular nitrile o-rings and reassemble. All it does is spin weights internally to move a valve back/forwards in the valve block so that it applies pressure to the ram inside the steering control unit. This is how it creates the artificial 'feel' in the steering.
If a re-seal doesn't work out, I think I still have a used one somewhere. However, someone local will likely have one.