Just thought I would let others know how I fixed the stripped coupler on my engine. As luck would have it I had a screw that was slightly bigger than the coupler hole for the factory screw. So I screwed it in and it broke off,but turns out that was a good thing after all.
So I used my dremel to grined it down flush with the coupler end essentially filling in the original hole.I then used a very tiny drill bit in my dremel to tap a new hole for the factory screw. I then scewed in the original screw very slowly allowing the screw to basically thread the new hole.
Then I re attached the coupler and made sure it was tight and would hold on snugly. I pulled on it aggressively and it held. So then I used some gorilla super glue to make sure the screw would not back out. Now it works fine. I checked all my other cars and put a dab of super glue on each coupler screw to ensure they do not work loose.
It all works now wonderfully. I must say after all this I am kinda disappointed that I had to go through all this with a new set costing 3,000.00,but thats lionel though and at lest now I can enjoy the set. Best of all when my new couplers come from lionel I will have 2 spares for any future coupler failings.