There is a leak that has not been able to be replicated by spraying around seals. However after heavy rains, water accumulates. What are the possible issues? The car radio has shorted out the amp fuse.
A lot of water gathers under floor mat after rains are there any common reasons? on 1991 Mercedes-Benz 300SL
Windshield gasket, Sun roof drains clogged, Door weatherstrip all of these items could be the cause of the leak
Most common is windshield seal. Try bring it to a window show and have it looked at.