hearthstone phoenix ceramic blanket replacement?

we've had our phoenix now 5 years.
during the cleaning last month in prep for heating season, we discovered that the ceramic fiber blanket has to be replaced.
we went to an authorized hearthstone dealer.....who sold us a blanket then could not tell us how to replace it!

he THOUGHT that maybe there was a bolt or 'something' inside to release the baffles that would lift out so we could put this in....
i can't find any information online about how to do this
does anyone here maybe know?

thank you so much
btw, the owners manual isn't much help either

vi

all of the dealers in this area are not very helpfull.
that's why i asked here.

thank you anyway

vi