Hearthstone h2 broken thermostat handle?

[motoman]

Hello,
I tried searching older posts but did not see anything on this topic. I have a hearthstone h2, and the thermostat handle that threads into the back of the stove, it opens and closes the vent. Well I think the stove was layed down on that side and they didn't take the handle out first, so it snapped off with I guess the threaded part broken in the stove? So the question is how can I fix this, since this is supposed to act as automatic type therm, opening and closes vent on its own as needed. I tried drilling out what was in that hole But no luck. If I look into that hole theres visual of any threads I can see. So not sure I can re thread, or adapt another way to hold handle in hole that still lets it move on its own?
Thanks for any help

 

[DAKSY]

Here's the page from the manual that shows the T-stat Assembly:

I would use a carbide drill to try to get the snapped off portion out, & if you are successful,
then drill & tap for the appropriate sized helicoil insert to give you clean threads to attach the new handle to.