hi mate, seat tilt handle broken i expect, very common problem with the st, mite need cables aswell but you may be lucky and just need the handle, the sloshing sound ur getting is probably inside the door, full up with water, the drain holes in the bottom of the door block up with crap and the door fills with water, just get a small flat blade screw driver or something and look on the very bottom edge of the door on the inside, find two drain holes one front one back, poke the screw driver in the holes and get ready for the waterfall out the door! hope this helps.