[Short Cast]

Try this, put a piece of tape half over the larger half & half over the smaller, but you don't want it to stick to the smaller half, you want to make a space where you can put a some soapy water into so it can soak into the joint. I would also attach a vibrating sander, remove any sandpaper first, to the rod maybe by the reel seat & turn it on & let it run to vibrate the rod to help work the soapy water into the joint, same idea as an ultrasound cleaner. give it a while to work & then try to separate. Hope it works. In the future you might want to cover the joint with a piece of tape to keep water out before you walk away from the car.