1993 Volvo 240 wagon, AT, 123,000 miles, acquired 1.5 years ago. I'm rehabing the transmission with periodic drain and fills using Valvoline conventional dex/merc. Did 6 last summer and 2 this summer. I chickened out on replacing the pan gasket and filter after reading about possible damage to the pan when trying to remove the dipstick guide tube. It leaks ATF only when sitting for a couple of weeks at a time, and then it is not a small amount (about 15 inch diameter soaked on the newspaper). I don't see a drop at all if I drive it more frequently than that. I have not recently looked underneath but in prior examination, I noticed a drop or so at the rear transmission pan, but I have no idea if that's where the leak is. I will plan to do another examination this week. I'm curious if this pattern might suggest something, such as a failed torque converter seal. ATF level is good. I suppose I should just do the pan gasket as the first step. Thanks.