Product review (5 stars): Don't take no for an answer, get to the right department of the manufacturer and obtain this part for free to fix design defect
Searched the Internet for leaking Whirlpool refrigerator (model GI5fvaxyy00) that also has ice build up under bottom mounted freezer and found a wealth of information on YouTube and here on Amazon so thank you to everyone that posted valuable information.  The following document lists the model numbers of refrigerators that potentially have or will have these [...], If Amazon removes the link then do a search for Technical Service Pointer W10632338A drain tube. You should find a document that lists the 1500 models, from various manufacturers, affected by the use of a duck bill check valve which plugs up and sticks closed.

If your model is indicated then contact your manufacturer. I have a whirlpool and sent an email through their customer service website, their response was for me to call their number during business hours so they could assist. Called number which has many options and after three transfers I got the Customer Care Team in Michigan, direct number 800-253-1301.

Spoke with a representative, Ricky, and informed him of the issue along with mentioning the Technical Service Pointer W10632338A (TSP-338A), linked above removed by Amazon. Ricky informed me that I had two options, a service tech could be sent or whirlpool could send me the part free of charge and I could install myself. Watching the YouTube videos this repair should be an easy project for the DIYer. I choose to have the part delivered for self installation as my refrigerator was bought back in 2011 and would not be covered under warranty thus a service technician would cost me money.

In my case whirlpool did the right thing and provided the part free of charge and without any fuss. Ensure you model number is on TSP 338A and don't take no for an answer and try different departments if necessary. Remember getting to the right department can mean the difference between yes and no, it took me three transfers to navigate the confusing maze of people and departments.

Again, thank you everyone for your posts.  The repair part is not that costly but it is the principal that companies should stand behind their products and fix design defects or make the process as easy as possible for their customers.

The drain tube has been installed for a little over two months and no more water on floor or ice build up under bottom freezer.  Installation hint, place a dry cloth/ rag under the drain after removal of old duck bill check valve then open freezer and lay hair dryer, in the pull out top rack, pointed toward the open fins in the back of the freezer. Once the rag is wet and a Qtip can be inserted fully up through the drain then it is likely unfrozen and ready to install the new parts. I would not suggest forcefully trying to break out the ice through the drain with screw driver, let it melt with help of a hair dryer, be patient it may take 15-25 minutes with assistance to melt, but do it right the first time so you don't have to go through all the trouble twice. Don't try to defrost with a hair dryer from the rear of the refrigerator where the new drain tube will be installed as it is insulated in the back so defrost from inside the freezer compartment itself.