Upper crank seal on 7.5

[Rude55]

I pulled the flywheel off and noticed a lot if oil covering everything. So I'm guessing it's the upper seal . Does anyone who how to get it out on a 1980 7.5. And should I do the lower one too? Also could leaking seals cause no power at times and no idle?
Thanks

[boats.net]

Never tried to replace seal without splitting crankcase but it might be possible, I don't think the seal has a locking ring around it that would prevent it from coming out of block.