Yep, I seen that before! Like every year.
The end of the steering cable has a telescoping like sleeve affair, the outer part of which is stuck with crud to the inside of the tilt tube. On the end of the sleeve, where the hole is for the drag link to the motor, it should have two flatted sides. You can put a crescent wrench on those flats and slightly turn it back and forth to loosen the sleeve. Just be careful to not turn it too far or with too much force if it does not want to break free. Just kinda wiggle it back and forth. Once it has some wiggle room, you should be able to push it out of the tilt tube. It ain't easy, but it will work. The steering cable is a stiff bugger, and it makes a pretty sharp bend at the inside edge of the boat where it heads up front. You'll have to do some finessing to get the whole cable to move far enough to extract the end completely. But this too shall work.
Another little trick that I hesitate to recommend (or am reluctant to admit I have tried) is to reconnect the drag link, tilt the motor up to about 45º, and reef back and forth on the lower unit as if trying turn turn the motor. That might get it to break free. Just be sure you don't break anything else.
Don't try too awfully hard to break it free using the steering wheel. There are lots of things between the wheel and the motor that could break instead.
Once you get it out of there (yeah, sure!), then you have to clean the hole. I have a 3/4" round spiral wire brush (like a bottle brush) that I turn with a drill motor to shine the hole. Go to an auto parts store and ask for a wire tube brush if you want one of those. Another thing you can use is a long rod with a slot sawed from one end to a couple inches up. Slip the end of a length of emory cloth in the slot, and wind it around the rod until it will just fit into the tilt tube. Then turn that with a drill. Clean, and clean, and clean until the hole through the tube is smooth with no more corrosion. Then clean the parts of the cable end, grease it up with a waterproof grease, and reinstall.
At the port end of the tilt tube, there should be a groove machined into the ID. I think there is supposed to be an o-ring or something in there to wipe the sleeve and slow down the crud getting in. I found an o-ring about the right size and stuck it in there the last time I did mine. We'll see if it helps.
Oh, and you are going to make a nasty mess in the splash well of your boat. Don't even try to keep it clean unless you are a fanatic about such things. Instead, when you are all done and the mess is wiped up (smeared around), get some Barkeeper's Friend and some rags and water and prepare to be amazed at how clean you can get the gelcoat. You'll have to wax it afterwards, though.
You gotta get this thing fixed. Cathlamet is a must-make. See ya there!