I've sure its been done but I've only seen one guy on this forum try it. He said it wasn't worth re-building it yourself. The seal by the pulley is called the front seal. The one by the impeller is called the main seal. ProCharger will replace both for $400. Mine was still under warranty when they replaced my main seal. The front seal cost me $140 because it was damaged by a shredded belt.
ProCharger P-1SC, 9 psi, STD 396/383; Uncorrected 388/375; SAE 383/370.
USAF 1969-1996: Vietnam veteran. Aircraft maintenance. ICBM Operations. Research & Development.
Also own: 1997 Harley FXDWG, 1998 F-150, and 2002 Corvette LS1