Had to go pull out a manual and look
it says "If the machine runs hard after standing idle for some time, use a little kerosene in the oiling places, run the machine rapidly, then wipe clean and oil"
I'm not sure I'd interpret that to be "soak in kerosene until it moves freely" and the part about cleaning the kerosene off is important. It will soften the old oil, but if you don't remove it, it will harden back up.