Need to replace my top rEGGulator, so ...

TWags15

... what's the best way to get the old one off? Didn't have any luck cranking up the heat. BGE guy on the phone said to tap ever so gently around the base until it shimmies free, but how? What happened was my sliding disc popped off when I got too aggressive with it during a freeze (I'm in Chicagoland). I can still magnetize it on there and slide it to control temp, which is fine for a low 'n slow, but it falls off when I open the lid when it's cranked higher for burgers and steaks. I'm not prevented from cooking, but I'd like to get the new one on -- and do it responsibly. 

Langner91

If you are careful, you can tap it from inside the dome using a dowel. The hole in the reggulator is slightly smaller than the dome.   However, have someone ready to catch your dome so it doesn't come out of the bands.

It will come off, it just needs some help.

This may also help:
https://eggheadforum.com/discussion/1228090/how-to-remove-the-cast-iron-reggulator-vent-cap

alaskanassasin

Heat it with a propane torch.