Before I had the new windshield put in, I cleaned the channel and found the metal to be in excellent shape. The original F8 shined like new.
I will probably end up removing the glass myself to eliminate the leak.
Dayclona is correct concerning new cars.. Most came unsealed between the glass and rubber gasket.
MOST WS's will leak there if not sealed after a replacement WS is installed...
Easy to look at the bottom gasket with a flashlight ( over the dash and usually in the corners) and see water tracks on the gasket... Pretty much tells if its leaking from there..
As also said above, leaks between the WS rubber gasket and the BODY or PINCHWELD are very common..
Get a friend with a hose and lay inside the car with a flashlight to pinpoint... Start the hose at the lowest point outside and move up from there.. DO NOT use any high pressure or a turn the hose on high.. All that is needed is to slight stream to find your leak source....
