Bob,
I am making a wild guess that you FINALLY received your 'K'! I would reply to your post for this reason alone, but I also suffered almost exactly the same damage on mine too! I couldn't figure out how it was caused, but yours offers a clue. Upon decanting the tender I had a little 'chip' of plastic fall out. After a lot of head scratching, I found that it was just as yours at the center of the cut lever. I also discovered the tender shell was loose. Upon removal of tender shell I also discovered two of the three plastic 'posts' coming up from the tender floor had sheared off. One was at the base, the other about 1/3 the way up.
I used regular plastic model glue to carefully repair all three items. The chip that was out of the rear of the tender fit back in perfectly, and unless you knew to look for it, you wouldn't know. The glue was put on the back (inside) so there was not an issue of it squeezing out the joint. The posts were very carefully glued back, and once fully set, were reinforced with epoxy. Needless to say the plastic was gently roughed with some fine sandpaper so the epoxy could get a grip. Somebody else on one of the forums had the post breakage too (at the base) and used screws through the tender floor.
Good luck with this,m and keep us up to speed with your progress with the 'K'!
Regards from Paradise!