i have fixed a lot of them with permetex right stuff gasket maker. drain the oil, unscrew the nut, clean it with about a case of brake cleaner, apply gasket maker around the dipstick tube holder and on the threads of the holder block and tighten the nut. use a lot of silicone, no one will see it anyway.
IF YOU REMOVE THE DIPSTICK TUBE DO NOT LET THE HOLDER BLOCK FALL INTO THE PAN. USE VISE GRIPS ON IT OR LEAVE THE DIPSTICK TUBE ATTACHED. IF IT FALLS IN THE PAN YOU ARE THOROUGHLY SCREWED. -GOOD LUCK its really pretty easy, make sure you clean away all the oil and use your head