'83 300TD's leaks, locks, and a little electrical

[Lulu's]

Hi All,
It seems like every day brings another broken little thing on my beloved 1983 300TD...

1. Water Leak: I've drenched the car with a hose and buckets of water, targeting all the usual suspects: sunroof, windshield, hood hinges, doors, windows, the whole nine... and I can't get water into the car. But leave it parked in a rainstorm and two inches of water accumulate in the rear driver's side floor pan. It's been over a year and I've taken it to two Mercedes shops... neither have seen anything like this and can't diagnose the problem. Please help!

2. Antenna: I recently had a new mast put in and verified that the motor was in good working order... but it doesn't go up and down. I fiddled with it and got it working for a couple days, but it's stopped working once again... my attempts at TLC haven't helped, and I just want to fix what should be a simple issue. When I turn off the radio the antenna doesn't budge but I hear the motor faintly click once. Any ideas?

3. Door Lock: My key broke off in the driver's door lock today. Got the key out, but now the lock won't turn. I'm afraid it's toast... has anyone had any luck repairing these or is it time to replace?

4. Rear Windshield Washer: The rear reservoir is full of fluid, and I hear the pump run when I push the button... but fluid only drips out (if I'm lucky). I've cleaned out the spray nozzles but still nothin'.

5. Dash Lights: Sometimes the battery, e-brake, and brake lights stay lit up for several minutes after start. No biggie, but I'm wary this is a sign of bigger electric issues...

Any assistance would be welcomed. Thank you!!!