|You probably could install another drive into the enclosure. However, you need to evaluate why the current drive has failed. If the enclosure is small, made of plastic and there are no cooling fans then overheating may be what killed the drive.|
The drive may still be under warranty anyway.
If this is an enclosure with NO external AC power supply then you may want to consider replacing it with one that does use AC power and has a fan.
The smaller, self contained units are designed for occasional use. If you have it connected always it can overheat.
One other thing to consider. Iomega does not make hard drives. Buy a unit from a company that actually makes the hard drives. They are more likely to build a unit that is designed to not overheat.
Finally, only use external drives for a second copy of your files. Not the ONLY copy.