I bought a brand new 580 ex 11 flash unit. When I turn it on it makes a grinding type of noise and then the zoom in the upper right coner continues to flash. I can't test fire it but the pilot light is flashing red. Is the unit defective?

Yes and no. Most likely, it needs to have old lubrication removed and replaced with new lube. You can decide if you want to pay to have that done, or not. If you choose to do it yourself, WARNING!!!
The capacitor will retain a charge for a long time and can give you a nasty burn if you get the wrong wires together!! A sudden jolt of high voltage can also toast the electronics. Be very careful.
Depending on your use of it, there may be a worn part dragging during the zoom due to the lubrication wearing out.
I have no idea what the repair will cost you. It will depend on where you have it done, and what their rates are.
Canon will not likely cover the repair. It is normal for things to wear out.
So the choice is yours. As long as it works otherwise, you can deal with the noise. If it bugs you, repair or replace it.
You might also investigate the Sigma ET 500 DG Super flash. Do your homework on features and pricing before buying. They run about half of a Canon 580 price. Yes and no. Most likely, it needs to have old lubrication removed and replaced with new lube. You can decide if you want to pay to have that done, or not. If you choose to do it yourself, WARNING!!! The capacitor will retain a charge for a long time and can give you a nasty burn if you get the wrong wires together!! A sudden jolt of high voltage can also toast the electronics. Be very careful. Depending on your use of it, there may be a worn part dragging during the zoom due to the lubrication wearing out. I have no idea what the repair will cost you. It will depend on where you have it done, and what their rates are. Canon will not likely cover the repair. It is normal for things to wear out. So the choice is yours. As long as it works otherwise, you can deal with the noise. If it bugs you, repair or replace it. You might also investigate the Sigma ET 500 DG Super flash. Do your homework on features and pricing before buying. They run about half of a Canon 580 price.

You can decide if you want to pay to have that done, or not. If you choose to do it yourself, WARNING!!!
The capacitor will retain a charge for a long time and can give you a nasty burn if you get the wrong wires together!! A sudden jolt of high voltage can also toast the electronics. Be very careful.
Depending on your use of it, there may be a worn part dragging during the zoom due to the lubrication wearing out.
I have no idea what the repair will cost you. It will depend on where you have it done, and what their rates are.
Canon will not likely cover the repair. It is normal for things to wear out.
So the choice is yours. As long as it works otherwise, you can deal with the noise. If it bugs you, repair or replace it.
You might also investigate the Sigma ET 500 DG Super flash. Do your homework on features and pricing before buying. They run about half of a Canon 580 price. You can decide if you want to pay to have that done, or not. If you choose to do it yourself, WARNING!!! The capacitor will retain a charge for a long time and can give you a nasty burn if you get the wrong wires together!! A sudden jolt of high voltage can also toast the electronics. Be very careful. Depending on your use of it, there may be a worn part dragging during the zoom due to the lubrication wearing out. I have no idea what the repair will cost you. It will depend on where you have it done, and what their rates are. Canon will not likely cover the repair. It is normal for things to wear out. So the choice is yours. As long as it works otherwise, you can deal with the noise. If it bugs you, repair or replace it. You might also investigate the Sigma ET 500 DG Super flash. Do your homework on features and pricing before buying. They run about half of a Canon 580 price.