You see, the Zip drive had a parked head. When the head came out to read the disk it would "click" as the head left it's dock and came out to the media. If it failed to read the media it would click again as it re-docked. This all happened fairly quickly and was the "click-click" sound you heard when a drive failed for almost any reason.

That proved to be a very difficult problem that ultimately led to the class action suit that I believe was the companies demise. It survived in name for a number of years, but really only in name.

The lawsuit itself didn't seem to affect the company that much but it affected policy a lot. Their next drive could have been the next big craze. It was ready way before compact flash came along but the company refused to ship it because the failure rate was slightly above 1%. We spent a few years trying to reduce the failure rate by fractions and we all know that a few years is ages is technology.