Keeping Gold min after gold all gone?

I need to know how to get the Gold mine to stay alive after its all been farvested. Iv looked under the unit eitor, advanced game contents, and iv tryed makeing a trigger for it. But no matter what I try it never works. So I ask, Does any one know how to this that I ask.

Create a trigger that says when the gold mine get's below 50 gold, remove the gold mine ability. That way it won't be mineable. If it's an Undead or Night Elf mine, have the building be un-summoned\destroyed and then remove the gold mine ability. If that doesn't work, when the gold mine dies, set it's location to a point variable and create another neutral building there that is an un-mineable gold mine.

Gold mine dies

Create Neutral Building - Gold Mine with 0

or
Gold mine dies
Create Gold Mine
Set gold in gold mine to 0

Don't gold mines automatically die after reaching 0 gold?

My gold mine is a Farm so I what it to be able to die when an enemy kills it. The farms are built with 0 gold and it renerates 1 gold every 4 sec, then a "Tax collecter" comes and get the gold. The best solution to my problem (I think) is to have a Gold Mine ability that does not have the auto-die feature on it. Can you help me with that? (More of a Custom spell question than a trigger one, I hope)

Thats what I was afraid of. Oh well more fun that way!

I think that's hard-coded into the ability... At least I couldn't find it anywhere...

[edit] - Looks like someone posted this while I was typing...