I posted this same problem on the tech side, but thought I'd repeat it here for the SL crowd:
After popping the hard top for the first time this season, was able to drive with soft top for first time since purchase, September 1990. Easter sunday took a two hour drive through rain, and ended the journey with the passenger seat making a series of its own adjustments......my wife thinks the car is possessed! It went into a full upright position, despite her trying to make corrections using the door panel controls......then I felt the floor behind her seat, and it was wet, so I assume the electric motors were shorting out and "self-adjusting". I tried to dry out the area with towels.......and that seemed to help.....next day, it was sopping wet again, and the seat would make its own adjustments, at intervals......It's now four days later, and the seat has stopped "self-adjusting", but the floor continues to be wet.

Am I collecting water off the soft top and into some internal area, like the rocker panel, then seeping into the floor area? Only seems to be the area behind the passenger seat........

Am scheduled for a shop visit next Wednesday, but would like to suggest some fixes, rather than have them charge me for their investigation. Did NOT have this problem until I took off the hard-top......and, ironically, the hard top had minor leaks in rain on both sides, at the A pillar.....which is inconsequential compared to this problem...

Any help???? Hope the seat adjuster motors aren't ruined....