Part for Drain Tube

https://samsungpartsusa.com/products/da63-00951b Might be a functional equivalent.

I don't think you need it. The drain tube on most brands does not have a "valve" in it because if there is any water above it, it needs to drop right out into the evaporation pan in the bottom of the fridge. It is that one little hole that can get blocked up by peas or paper and will cause the fridge to malfunction because of ice buildup and/or leaking out the front door during defrost cycles. I can tell you from experience that Samsung and LG have a bunch of stupid bits installed to fail so that customers buy new ones after the warranty is up.

The check valve is there to prevent hot air from below getting into the freezer. When it went bad, the freezer could not reach set point. After replacing it, everything worked right.

The check valve was at the top of the tube, and heat eventually made it brittle and it broke.

I am going to modify it to the bottom instead.

I have found some "duckbill check valves" I think might work.

I'll let you know how they work out.

You are right about that, I think. My previous refrigerator had no check valve, just the end of the tube going into a sponge. This reefer has been a pain since it was new. The defrost drain tube would freeze up, and then the water would accumulate under the crispers. The improvement kit they offered did not help, so I made my own way to keep the tube from freezing. I described it in a previous posting. It still works great.

If they had lengthened the defrost cycle a few more seconds, the problem would not have occurred.

I think I may have found a simple solution to prevent the hot air from the compressor and condenser from getting into the freezer through the drain tube.

A a "P" trap like under a sink will keep the fluid in it till it goes above the top of the bend, then it will dump it out, but the trap will remain full up to that point.

Think that will work?

That should work until the water in the trap evaporates.

The factory fitting/valve that is being removed… does it also function to keep the already mentioned errant frozen pea and other detritus out of the drain tube?

I can answer that one. NO. It will clog faster and sooner!

If the water evaporates, it will be filled on the next defrost cycle. The drain tube connects to the pan under the cooling coil, and drains the water when defrosting.

This would keep the trap full, I think. As far as trash in the drain tube, the tube is not open to food or debris, it is high above the food and behind a cover plate

Perhaps you could find a similar junk refrigerator somewhere? Check appliance dealers that take old refrigerators in trade, or look on your local CraigsList, Facebook Marketplace, or similar for an old refrigerator.

Lots of duckbill valves on Amazon.

A few drops of cooking oil on top of the water would prevent evaporation, and the oil would always float to the top as a seal to keep the bend full.