I had the same problem it started with the rear flange leaking and then moved to the front as well. I also replaced my seals which slowed the leak but didn't stop it. My problem ended up being blown out bearings inside the transfer case. Try removing your driveshafts and grabbing the flange I bet it will move a little. Its probably time for a rebuild or a new unit. FYI...... Get a new unit its way easier and you can get the lower gear ratios that you want. Send yours to Marlin for the core charge.