I heard what you're describing too, but I don't know what to do about it! I was planning on posting on the help forum, but I don't think there's a way I can fix this recording after the fact. I'm willing to record it over again if it's really necessary.
Robin, I think posting for help is a great idea I would hate for the same thing to happen for your longer recordings. I recommend posting in Listeners Wanted. Let them know it starts ~1:30 and what type of mic you are using. FYI: There is also the sound of a door closing in the background.
I took a look at the file in Audacity and you are getting clipped. You may want to lower your microphone input. Under [view, show clipping] this will indicate the areas that really need to be adjusted. Alternatively, I selected the entire piece and amplified -2. That brought the overall volume down to a better level but you are correct that it does nothing for the crackle.
I'm a soft reader and always have to amplify my recording up. Get ahold of Starlite, she is also a loud reader, and great at providing technical assistance. She seems to be very active in Listeners Wanted.