I've used numerous on jobsites over the last 30+ years. Kroil is the best I've found.
PB Blaster is pretty good also.
Secondly, you have 2 very dissimilar metals. Steel and aluminum. They have different expansion rates. Maybe bring a little heat to bear. As they cool, break them loose.
Someone suggested using a soldering iron to localize the heat, and thus protect the adjacent neoprene feed rollers. That, plus a high grade penetrating oil, and patience, sounds like the key.
Thanks for your help.