Troy 85 RX-7

I'm having rear main seal/oil leak issues that I can't figure out. My car is an 85 SpecRx-7 with a reman 12A (emissions equip. removed). I don't know the history of the engine as I bought it used. The rear main seal failed during the car's shakedown run at an autocross a couple of weeks ago. When I changed the seal last week I found that it was partially torn and pushed out against the flywheel. I assumed that it was just a bad installation, so I replaced the seal as well as the stationary gear o-ring while I was in there. I made sur the outer seal surface was completely dry and the inner lip seal was lubricated during installation.
I took the car out last Friday for a lapping day at my local roadcourse Friday and experienced oil leaks around the seal again and was getting lots of oil in the vented catch can I have attached to the filler neck vent. The other vent fitting on the intermediate housing is capped. I pulled the flywheel inspection plate today and noticed the replacement rear main seal had pushed out against the flywheel again.
The engine does not smoke, but seems to be down on power. I checked for blowby, but I don't see any signs of pressure coming out the oil fill vent. The possible causes that I can come up with are: the oil return passage from the rear seal housing to the pan is plugged, the oil passage thru the eccentric shaft from the rear main bearing is restricted, or the bearing clearance is out of spec allowing oil to blow into the seal housing. I'm new to rotaries. Are any of these scenarios likely or common?
Thanks,
Troy