I'm willing to bet you have a MiniScribe hard drive. These drives were prone to failure in the first place and seem to be failing at an alarmingly high rate as of late due to age (nearly all of them are 20+ years of age today). You're best off replacing it with a Quantum ProDrive LPS (easily pulled from an LC) and doubling your capacity to 40MB while doing so. (Of course, you can always take it higher than that).