My niece's '98 would only work on settings 3, 4, and 5. I replaced the blower motor resistor and now it works on all settings.
I thought removing the blower motor would make access to the resistor easier...well, it was, but putting it back required me to learn yoga and become a contortionist. Seriously, it's not difficult, but an extra hand to hold the blower up while I tightened the bolts would have been nice.
Anyway, I'm glad I took the blower motor out as I discovered some leaves and pine needles stuck in the fins of the squirrel-cage. I cleaned everything and reassembled it all and now not only does the fan work on all settings (see above) but it's a lot smoother and quieter on the higher speeds as well. The pieces of nature I removed must have been causing the fan to be unbalanced, so if anyone is having an issue with a rumbling or roaring sound on high speeds, this might be your problem.