How can I remove very stuck headset spacers (alu/carbon) Working on a bike that has had significant indoor turbo usage, (i.e. a lot of sweat has run down the headset) and corrosion has bonded the aluminium spacers to the carbon steerer. The steering is stiff and notchy such that the bearings must be replaced, but the spacers are well and truly stuck in place.
I have tried getting some boiling water on the spacers, wrapping a boiled cloth on there, I spent a few hours dripping lemon juice down the gap (I think I read that on Park Tool), I've tried WD40 and have tried turning the top spacer with slip joint pliers (water pump pliers) as hard as I can, but no progress.
I will not want bang on the top of the carbon steerer any harder and the alu piece on top is proud because the bung is seized in place also (still functional). My experience and exploratory taps say that no amount of hitting on top will free this headset up.
How can I remove these very stuck spacers without damaging the frame or fork? I'm hoping for a proven answer because if I continue but damage the spacers further without getting them removed then I potentially make the bike unsafe and so unrideable.


Update:  I am still looking for an answer. Nothing forthcoming just yet. I'm thinking that somehow cutting through just the spacers, maybe with a rotary tool, would do the trick, a-la DavidW's answer in the first comment.  Maybe cutting not quite all the way through and then forcing the ends apart to pry them off. I asked in my trusted local shop at the time and they said they would do something similar but were too busy to take it on.
I went ahead with the rotary tool (Dremel) and general cutting disc. I cut two grooves side by side in the top spacer and prized one of them open with a flat screwdriver. Once the aluminium is thin enough, it will snap open with a little click, so it isn't necessary to cut all the way through. I carefully cut a little deeper each pass and tested with the screwdriver, managing to find the point it would snap open with the tool never touching the carbon steerer.

The top two spacers were removed in this manner, but I didn't want to cut through the silver spacer or conical spacer as they would be awkward to replace. That meant I couldn't cut vertically through the third spacer using the 38mm cutting disc. See below, I cut vertically as far down as I could and then ground away the spacer with a horizontal cut until enough was removed to snap open the spacer. That was the hardest part with the rotary tool to avoid damage to the steerer below but with patience it was doable.
It looks a little rough photographed up close, but it was careful and patient work with no damage to any carbon parts and minimal nick to the silver spacer.

Now I could remove all the spacers and had just the compression ring to remove. This had seized onto the steel inner race of the top cartridge bearing, meaning the whole assembly was still stuck together. I tapped the steerer tube down to raise the ring up and cut through the steel race, minimising touching the compression ring to preserve it. I didn't want to drive the fork all the way down in case the metal would gouge the carbon. The ring did get a little roughed up by trying to prise it up beforehand, so this was treated afterwards with a file to remove the burrs. They were really stuck together and even off the bike it took some force to separate them.

I don't think the spacers were bonded to the steerer by corrosion, but rather the gap that would let them spin was packed with the white yuck, so they were jammed in place. Once the spacers were prised open they slid off quite easily. If they were bonded on it would have taken much more force. The compression ring however was (galvanic?) corroded into place and meant that tapping down the steerer would have been futile while spacers were still jammed on.
The old bearings were removed and everything else cleaned up nicely. New bearings and spacers went on and the steering felt like new again.