A 50/50 mix of ATF and acetone is the best penetrating/freeing mix I've used.   

I got one of them out using a slide hammer. But the other one won’t budge. So as the old saying goes. “Get a bigger hammer”. Which my son says he has a huge slide hammer. I drilled a hole thru a spare tube cap. Then I ground down a hex nut to fit up inside the tube cap allowing me to attach a heavy duty eye bolt for the hook on the slide hammer. It took a lot of hammer hits at about 1mm per hit. I assumed there were bushings inside the lower but I see it is just a close sliding fit. Thankfully the chrome tube is in very good condition. No witness marks at all from being seized in the lower. The seal came out fairly easy on the one that I got apart. To be continued tomorrow!

youtube.com/shorts/1g0nIn9L2pQ?si=4Id5kEQ0Et-bfcWB
 

Will it not move down at all. Assuming it's not already bottomed out.

It is seized in the fully raised position. I did remove the spring clip retainer, washer, and then used an exacto knife to trim away the rubber lip on the seal so that I could get some penetrating oil in there. I removed the screws in the bottom of the lowers.

I’ll get it when I bring it to my son’s house tomorrow. He has a good heavy steel bench with a mega vice. My vice is mounted to a makeshift wood bench that was walking across the floor as I worked the slide hammer which doesn’t help with the effectiveness of the tool.

I just noticed you asked if it would go “down” at all. No it wouldn’t. I slammed it down onto a steel plate several times with no movement. I hit hard enough to almost ruin the two studs. I put hex nuts on them but they went bow legged. I can still use them though. I just had to open up the clearance holes a smidge on the cap. 

Edit:
I scavenged two studs and the saddle cap from a damaged set of forks I had in the barn. I don’t scrap anything…..for this very reason.

That such an unusual situation. Have forks had water in. Should sent the story & pics to whom you bought them off. I guess he didn't know quite how it was.

OK, thanks. I guess there's more to come, & good luck with that.

How about a week-long vinegar bath that might eat the rust off? Then again, it might do the aluminum in too...

Bigger Hammer got’r done!
Lightly honed the aluminum corrosion from inside of the lowers. New seals and dust caps ordered.

Oh wow, amazing perseverance. I probably would've given up & binned them by now.