Product review (5 stars): Great Product - a few application suggestions...
As others have attested to, this is a great product that will extend the life of your dishwasher racks - highly recommended.  Here are a some tips to add to what has already been suggested:

-  Examine your racks carefully before starting and mark each spot that needs fixing.  I wrapped strips cut from Post-It Notes around those areas.  Don't bother if you have a large number of spots as some reported, but in my case I had only about fifteen.  I didn't want to miss any or forget to do them and have to go back a second time.  You'll probably discover more problem areas as you go, so fix them as you go.

-  The instructions say to wipe off excess touch-up compound after pushing a tip over a rack tine.  Whatever for?!  That stuff is basically the same compound that they dip the racks in during manufacturing.  I had repaired my dishwasher racks with a similar kit (not the same one) about 5 or 6 years ago.  Two tips from that repair had failed and fallen off, and another looked like it was beginning to show signs of rust on its edge.  This time I applied extra compound around the edge of all the tips to ensure good seals.

-  Because the compound dries extremely fast and the brush clogs up, just use the brush as an applicator of drops.  Brushing doesn't work well.  You can use the tip of the brush to help the compound flow a little while applying.  Some have reported that it likes to flow too fast initially.  I found that blowing on the touch-up compound immediately after applying it halted any flow.

-  Also because of fast drying, I pressed a little plastic cup upside down on the top of the bottle as I worked.  I used one similar to those little cups found in fast food restaurants for dispensing ketchup or salsa.  The whole time I worked on my racks the bottle was covered except to get a drop of touch-up compound.  Only the very tip of the brush went into the bottle until I was all done.  After finishing I cleaned off the top of the bottle and screwed the cap down TIGHT.  I'm hoping it lasts for the next time! :)