I have a '23 People S 150 with about 1500 miles. I was on vacation last week, and when I returned, I noticed a small oil spot on my garage floor under the rear differential. I appeared to be wet around the drain plug. Last year I bought a aftermarket drain plug with a magnet. The plug appeared to be tight, but I drained the differential and re-filled with new oil. When I re-installed the drain plug, I used plumbers' tape on the threads and torqued it to 7 ft lbs. If this doesn't work, should I go back to the factory drain plug?