Try fishing a clean cloth rag attached to some stiff wire in through the opening for the clutch fork/HTOB lines and rub it on the bottom and sides of the bell housing. Retrieve the rag and look for signs of hydraulic fluid. There should be no
oil/fluid on the inside of the bell housing. Just make sure that the rag is securely attached to the wire, or now you will have to remove the transmission to get the rag out.