I'm back home again and able to writeup my approach to repairing the door tab better.
The left tab that holds the bottom door shelf broke off while driving on some really bumpy roads (That's eastern Oklahoma!). I only had a quart of milk and a couple bottles of water on the shelf, so I suspect the tab may have cracked a little bit over time and the bumpy road was the final straw. See PIC1 that shows the broken tab.
I decided to recreate the tab using J-B Weld 50139 Plastic Bonder
https://www.amazon.com/J-B-Weld-50139-Plastic-Adhesive/dp/B01IBOK7FE/ref=sr_1_3?crid=30O1CUVJ3GTJ2&keywords=plastic%2Bepoxy&qid=1655164969&sprefix=plastic%2Bepoxy%2Caps%2C139&sr=8-3&th=1 using the shelf as a mold.
The fine print. Please read.
This epoxy is black. I could not find white. When done the tab is hidden by the shelf. That was OK with me and no one will see it unless the shelf is removed..
This approach creates a tab longer than the original. It extends from the bottom edge of the door up to original height, i.e. the full length of the slot on the self end. The good news is that this makes it stronger since there is more surface to attach it to the door. The bad news is that it means you can never reverse the door hinges (flip the bottom of the door and use it as the top) because that gap between the original tab and the end of the door will be filled in and a shelf will not connect in the opposite direction. The floorplan for my PC prohibits me from wanting to reverse the door hinges so I didn't care. If it does matter to you, then you'll need to trim the tab down to match the size of the original tab in step 8.
You will need a piece of cardboard, masking tape, olive oil (any other light cooking oil will work), some aluminum foil and Saran wrap (or other soft clear plastic food wrap). I took the door off so that I could bring it home and work in air conditioning,, but I don't think there is anything that would keep you from performing this repair with the door attached.
1. Remove the shelf from the door, if you haven't already. You need to lightly oil the slot on the end of the shelf where the door tab broke off.
2. Attach a piece of carboard across the bottom of the shelf with masking tape. This cardboard forms the bottom edge of the "mold" for the tab that you are creating. The existing slot in the shelf is the left, right and arched top of the "mold".
3. Then take a 3 inch by 3 inch piece of Saran wrap and press it into the drawer slot. You want to eliminate all bubbles, wrinkles, folds, etc. This effort will give you a better looking tab, and the oil will make sure that it doesn't bond to the shelf.
4. Mix the epoxy on something disposable (paper plate? couple layers of aluminum foil?). It really doesn't take much. I used less than a 4th of the tube. You'll need a little bit for step 9 as well. Completely fill the mold. The oil will keep the plastic wrap stuck to the shelf,, but be gentle. You don't want to move the plastic wrap and mess up the face of your tab.. You'll want to over fill.... just slightly. Filling it too little would create a thin tab & leave slack and that means that the shelf might slip off. Filling it too much and you'll just end up sanding more off later. Try to make it as level as possible, but it doesn't need to be perfect. Save the epoxy mess left over from the mixing. You can use it as a judge to see when the epoxy is cured and not disturb the new tab until you are SURE it is ready. Prop up the shelf so that the new tab is on top and level. I set a water bottle inside the shelf to hold it.
See PIC2 of my fresh epoxy in the plastic wrapped "mold". and PIC3 waiting for it to cure.
5. Wait for the epoxy to cure. By bending the leftovers I could tell a difference between 2 hours, 8 hours and 24 hours. I got impatient at 24 hours and proceeded. I also waited 24 hours because the humidity was very high. When cured the new tab will be stiff, like old dry leather. It does not get rock solid.
6. Remove the cardboard. The new tab should pop out easily with the plastic wrap attached. Gently lift the plastic wrap and the tab should release easy. (you can clean the shelf now, sorry for the oily mess).
See PIC4 of the new tab, and PIC5 for the smooth shiny face of the tab..
7. Prepare the fridge door for the new tab, by cutting off the broken tab, and lightly trimming anything that sticks up. I needed to lightly sand a few bumps.
see PIC6.
8. Now you need to prepare the new tab for use by cutting off the extra plastic wrap and sanding the BACK side. I sanded a little bit, inserted it in the shelf slot and fitted it in the fridge to see how tight it was. Also check to make sure that the shelf is resting against the face of the door well, and front to back & left to right level. if the new tab is too long then the end won't seat as low as the other end... I then sanded a bit more and refitted,,, again and again until I was happy with the fit. Be sure that the tab is being pressed against the door by the shelf when you're done. You need a slight amount of pressure for the next step. IF you sand off too much, then add a thin layer of epoxy to thicken it, or make another tab.
See PIC7
9. Now you can attach the new tab to the fridge door. Mix some epoxy and apply a thin layer on the back of the tab and a thin layer in the hole (on the foam insulation) on the door, I didn't apply epoxy to the white face of the door directly, I felt what was on the back of the tab was enough. If you put too much then you will have squish and will need to remove some. Next, put the tab on the door. You should be able to position it using the old hole as a guide. Then slide the shelf into place over the new tab. It will help hold the tab tight against the door and find tune the position of the tab... again double check that you are level and tight against the door. Wait again for the epoxy to cure. If you have the door still attached and the fridge in use, i.e. COLD.. you may need to wait a long time to the epoxy to fully cure. You should tape the shelf securely in place with masking tape while it cures. I had my door off the fridge and I just left it laying flat on a table while it cured.
I didn't take a pic of it in this state because you couldn't see anything but the shelf in the normal position, but here are 2 pics after it cured and was ready.
See PIC8 and PIC9.
Summary.
This was easier to do that I had feared. I was worried about ruining the door or the shelf, but the plastic wrap protected the shelf and bonded to the epoxy. It created a very nice smooth face to the tab. Better than I expected. This plastic epoxy seems to cure a bit slower than other epoxies I've used, so no need to move lightning fast. I've since driven over some really roughs roads (Texarkana to St. Louis) and the new tab did very well. I suspect the new tab is stronger than all of the original tabs, but time will tell what breaks next.
