Unsticking corroded jib track

[pipnosis]

The jib lead tracks on my boat are in a poor state and need replacing. The cars themselves, however, are heavy duty Garhauer ones and are in great shape. The problem is that the cars are aluminum and the old track is bronze, and the two have more or less welded themselves together.

Any ideas for getting them apart?

I am in the process of waiting for CorrosionX to do its work, but it's been a few days and no sign of success. I'd rather not buy new cars; they are $350 each.