are you sure it is the seal leaking, sometimes the blind needle roller bearing can leak
and appear to becoming from the seal have a look at Caulky's pic the bearing is just below the seal.
Also is your seal a tight-ish fit in the case? the casing should be warmed up when installing the seal.
Again in Caulky's pic you can see two punch marks at each side,
this is not a good way to tighten it (No blame on you Caulky mate)
you are better off wrapping the seal with PTFE (thread) tape before you install it.
If it is the blind needle roller leaking you can bodge it by cleaning the recess with acetone (nail varnish remover)
then fill the recess with silicon gasket goo, this is temporary but can work,
again the case should be heated when this bearing is fitted.