Quoted from Alan_L:
Tried the hot/cold trick again this morning, no luck. Tried whapping and tapping with rubber mallet, hammer, etc. without success I poured a lot of penetrating oil between them and I'm going to let that sit for a while. Then I'll try the wood stick and ice jacking approaches. And, no, my wife likes a good joke, but she's not that cruel.
Ive had good success boiling them under water in a large pot.
Put a weight on them, sideways if itll fit.
The pressure builds in the air void and pops them free in about 15-20 mins
Might work for you.