Thanks to BigL for his comments regarding the possible causes of the blower motor only working when speed 5 was selected. I had the same symptoms with my 97 GP.
I replaced the heater resistor first. It's not really that bad to change as the two rear screws at the back that are hard to get to only need to be loosened, not removed. The holes in the resistor mounting plate are slotted, so when the back two screws are loosened and the front one removed, it slides out easily.
Unfortunately that didn't fix the problem and I was sceptical about replacing the ignition switch to fix a blower problem that affected the daylight running lights. Especially considering it cost $260 from the dealer in Canada. As GM listed 16 different switches for that year, I figured the dealer was the safe way to go.
I started the job myself, but as mentioned by BigL, the female torx sockets are a must to get the top cover off the steering column. As I could find none in town, I ended up taking the care to a local shop to finish the job for me.
It was worth it in the end as replacing the ignition switch c/w wiring harness did resolve the problem of the blower not working on fan selections 1-4.
Thanks for the help.