The problem occurs when the car 'reaches that certain age' and the exposure to moisture causes a build up of rust which compromises the seating of the seal. I sorted mine by applying mastic sealant under the seal in the relevant places.
If water can be seen on the top of the seal then apply the mastic on the outside along the bottom and front edges and lower rear corner between the seal and the glass. Prise the seal back from the glass first and wipe it dry then use a fine nozzle and get the mastic in deep
If it's coming in between the seal and the metal frame then it's easiest to apply the mastic from the inside after prising up the visible part of the seal. Partially remove the wheelarch trim so you can get at the whole length.
For professional help try a body shop or auto glass specialist - they should know all about that window because it's a common target for break-ins.
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)
Last edited by Mick J; 01-03-2003 at 06:28 PM.