You have to get between / underneath the motors where you can barely reach the filters but you can't see them. You will know that it is off when the oil runs down your arm and drips off of your elbow. Another sign that the filter is off is when the oil wrench falls and breaks the bulb on your lead light.
To put it back on, try to remember where it came off. After about twenty minutes of tearing your arms to shreds, work yourself out of the oil, sludge, and waste water infested bilge and drink three beers. Come back tomarrow and try again. Good luck.
Jim