Cajun's idea is a good one, as I had to do that myself. Also, keep all of your
sealing surfaces clean, as dirt in these areas can cause water or dust leaks.
An occasional wipe with a wet cloth and a mild cleaner will help to keep the
dirt off of these sealing surfaces. Another trick is to get in the back of the
Trac when its dark, with a flashlight and shine it on your sealing surfaces while
someone stands outside to see where the light is shining through. The areas
where light shines through may be areas that you need to pay closer attention
to for sealing. Hope this helps.
By the way, musty strollers SUK!