I was actually able to repair mine. First let me say that high temp silicone ane liquid steel type products were a waste of time. I took the part to a welding shop and was told that they were afraid that if they tried to braze it they would cause a bigger hole. I ended up using a very basic Bernzomatic oxygen/propylene setup that I purchased at Home Depot. I used a few of fire bricks to make a kind of oven to concentrate the heat and prevent damage to the concrete. This was my first attempt at brazing and I have no experience with welding so if you are not experienced it would be much safer to have it done professionally. My only point is that It is possible. It may not be cost effective and if you should attempt this make sure to do plenty of research since there is the distinct posibility of fire, severe burns, eye damage (exploding concrete, etc.) Welding goggles are a must so again, Danthurs suggestion is certainly valid.
1995 Bonneville SSEI
1994 Buick Park Avenue