1971 CB750 oil leak. Replaced countershaft seal to no avail.

[Jakevidio]

I've got an oil leak (about 1 quart per 100 miles).  The best I can see, it's leaking from down low on the rear of the casing, where the chain is coming out.  Some mechanics swore it was my countershaft seal and encouraged me to let them replace it.  They said they replaced another one of the smaller seals right nearby as well, but the leak has not let up one bit.  I paid $230 for this bogus repair and the guys won't even inspect it further to see what else it could be.  Did I just get taken for a ride?
Any insights based on location and intensity of the leak?

[Re-run]

Have you checked to make sure there are no cracks in the case?
It may also be the shifter seal but not likely.
Have you checked the oil pan at all?
Some shops love to soak a person for repairs.

Get some simple green and a hose and clean the bike up and see if you can find the source.

[Jakevidio]

I think I found it!  I got some simple green and really cleaned the crap out of it yesterday.  I rode it to work this morning (to get it warm and get that leak dripping).  I was able to see a little better where the leak was coming from... the bottom of a cluster of rubber hoses behind the oil tank.  When I went to push them out of the way, one of them popped loose at the bottom and let more than a few drips go.  The hose came from the middle of the back of the tank and connected to the top of the far back end of the casing.  The end that popped off was completely split, hardly anything left of it.  I gave it a clean cut and reattached it the best I could for now but the hose is very dried out and cracked, I'll have to order a replacement today.  Hopefully this is all that was creating this mess.  
I was reading through the manual to see if I could figure out exactly which hose this is.  The best I could come up with is its the return hose for the scavenge pump.  Am I way off?

[Re-run]

Good find! It is either the return or sending hose. I would probably replace both hoses if one of them is that bad.