You posted in the TJ forum, your 94' is a YJ.
But yes I would start with checking the fluid.
If you are certain it is coming from the transfer case it would be a good idea to pull and look inside. They are not as difficult to work on as many people think.
Do a search on SYE install there is a good write up splitting the case on working on it to give you an idea.
Picking up a manual would also be a good idea.
Your transfer case is a NP-231-j