Lionel tether connection between tender & locomotive

The tether connection keeps coming out of the locomotive port during operation. Yes, it is secured firmly from the onset but either through vibration or the tug on the tether around turns works it loose. Any suggestions on how to keep the tether secure would be appreciated.

I don’t know enough about Alene’s Tacky Glue, or however it is spelled, and if it remains tacky for a long time, but a small thin swipe of that only on the thin sides of the plug might help. I would not want to have to do this to use the engine because the glue might go places it shouldn’t.

Is there a thin tape you could wrap around the plug, say only one layer, that might help to wedge it in place a bit more securely?

It has QSI for a decoder, I believe. Perhaps QSI might know how to help.

Maybe a tape like masking/painters tape might work. I was also thinking a small amount (spot).

A small dab of hot glue might work. Your thoughts?