Our garbage disposal was turned on with something that shouldn't be in it in there. It all got destroyed and ground up except for this metal piece, which got wedged under the "teeth" of the disposal. I've removed the disposal from the sink and turned it upside down to crank the thing around with the hex nut on the bottom, and everything fell out except for this metal piece which is wedged in there. I've tried getting pliers in there but I just can't budge it. If I put a sturdy flathead screwdriver on it and smack it with a hammer, it moves a little but doesn't dislodge. I could probably hit it harder but I'm worried about damaging the disposal. Would it be safe to use some silicone lubricant or something else in here to help remove the piece? When I turn the thing around, the metal piece scrapes in three places around the edge.
(newbie, so can't comment)
It is unclear whether you can turn the "tooth" with respect to the rotor--it seems like you can turn the rotor around with the hex nut on the bottom. Instead of whacking them with a hammer, I'd try holding the rotor with a wrench on the hex bolt and trying to rotate the 'tooth' with respect to the rotor with a wooden bar or something that can fit between the wings of the tooth. Think of holding the hex bolt in a vice while using a crowbar-end as an extra-big screwdriver to rotate the tooth. On my old disposal we used to use an old 4' long broom handle chunk to pry things around in situ.
Silicone should be OK, but if you are worried, normal cooking oil should do the same job and be compatible with anything in the garbage disposal can normally choke down.
There's usually a hole on the bottom end of these diposals which fits an allen wrench (hex key). Use that to work the the grinder back and forth until you feel it loosen. Then pull the metal out. The hex key hole is put there on the bottom so you don't have to whack around on the blades with a screwdriver, broom handle or whatever.