Advise for leak-proofing a 770 stand?

My 770 stand is leaking into the computer storage cabinet.
It looks like there are small pin-holes near the welds, where the trough is welded to the base.
The problem is, that I cant see where they are, because they are on the backside of the trough, and up near the top.
I'm totally at a loss as to where these leaks are coming from.
I can't see how there could be a leak there.
Hhhhmmmmm........
How can I stop these leaks?
I tried that spray-on rubber stuff (AS SEEN ON TV!! :) ), but it still leaks.
I also applied silicone all around the tray, bolts, screws, etc.
No luck.
Any advise?