pulled down on his chin? Like, you put your hands on where? I am curious.
The horse I frequently ride has recently gotten resistant about taking the bit. He is 17 hh, so I have been working on making him lower his head and then am super patient about having him open him mouth and take the bit. But, he has been just refusing . Never had that problem before.
So, I am going tot maybe try the old trick of wrapping a piece of "fruit by the foot" around the bit . I hate to resort to treats, so am open to advice on this same issure as the OP.