If the dry side is sucking air you should have a very high idle or a run away issue with engine rpm, or the engine might run flat and not make any power. Some times on the dry side you can see fuel/oil mixture lying in the flywheel cover. Wet side it's going to suck in gear box oil and smoke alot more than normal. Spark plug could have some sign of oil deposit on it.
I don't believe you have to split the case for that one. Kawasaki's usually do. If you are losing oil and fouling plugs, the right side might be shot. If you are showing signs of running lean then the left one might be gone. You should be able to do a leakdown test to see.
I had one and it would hold 5 psi for quite a while without any loss. If you pull the clutch cover off, you may be able to see of the seal is accessable from the outside. You should have a manual, it can save you from fouling up your bike. I am in the midst of a right crank seal on my 80 rm250 and to get to it you need to remove the crank gear. Without a service manual I would never have known that the threads on the nut there are left handed.