Pretty much. There's not a whole lot to them.
There's only a few places to get a leak. Most of them leak (at least a little) where the drum goes into the main case. Other than that, the only possible places are the shaft where the brake attaches, the motor mount, and the clutch cover.
Unless you do a full rebuild, there's nothing you can do about the first two that I mentioned (and they very well may be no better after), but the other spots are easy enough to take care of with your favorite gasket sealer.
It's also worth noting that these things only get a very small amount of oil. Unless the winch has been on it's side, they rarely leak out, but leaking water in is a whole different story if you go through deep water. If you only dunk it occasionally (or not at all), you can just change the oil afterward. If you need a solution for deep water, let me know. It's a bit more involved, but I have a solution.
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” ― Robert M. Pirsig, Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values