Once the wire is cut it just unscrews. There is a separate bottom and top piece to the canister with a metal mesh filter in between. You should be able to just clean it up and reinstall. You can do it without draining the oil. If your hydraulic oil is at the correct level you may get a little draining out the bottom bolt hole in the side cover. I just stick a bolt back in the hole to stop the oil from trickling out until I'm done.
If you don't find you have a filter you can take a look inside while you have the side cover off anyway and check for leaks.