Sounds like you need to remove the dipstick again, and reset the rubber ring back on correctly, part #306......
But that is just another "wild" guess without knowing, but a lot cheaper fix.....
I remember those drain plugs being plastic, hard to crack the sump then. And most Toros and Lawnboys had a bunch of crap in the way, anyway, so folks would change the oil out of the dipstick tube orifice......
Plus all of that oil is on the top of the deck......