Well, I took my 52 Chevy Styleline out today and heard this clacking around under the valve cover. I pulled off the cover and found that the 2nd rocker arm closest to the firewall was broken. I'm curious how hard this is to replace and if anyone knows a good place to get a replacement without having to buy all 12 rocker arms? Any ideas how this would break?? 32,000 original miles, never any sludge or gum buildup, nice and slick...just old age?

The rocker arm broke because the valve stuck in the guide. You will find that the push rod is also bent. Common to happen on intake valves and is caused by "old gas". The old gas forms a varnish on the lower part of the valve stem and you know the rest of the story.
The valve should be freed up. You can begin by squirting Marvel Myster Oil through the valve spring onto the top of the guide with hopes it will free up the varnish. Pouring the MMO through the carburetor air intake with the engine running at a fast idle will also help to prevent this. It is possible that the head may need to be removed it the MMO steps do not work. I will check my rocker arm supply and see if I have a #6 cyl. intake rocker arm.

I have a new rocker arm. If you need a push rod you can order one from NAPA.
After you squirt the MMO on the guide tap on the top of the valve with a hammer. This should move the valve a little and hopefully un-stick it.

I am a real believer in Marvel Mystery Oil and if it does not work to loosen the particular intake valve, try squirting PB Blaster (aerosol can) thru the valve spring and let it soak in for a couple of hours, then squirt it again and then tap on the top of the valve stem lightly (while you have the rocker shaft and rockers off) PB Blaster is a very good penetrating and it may work, however don't use it like MMO for a upper lube, just to get a stuck valve moving again.

I have had great results with Marvel Mystery Oil and stuck valves. As Gene suggests tap on the valve after soaking with MMO. Then once the valve is freed up and you have straight pushrods in the motor, turn it by hand. Then soak it again. Do this a few times, then soak it down and let it sit over night. The next morning turn it over by hand and watch the problem valve, if its sticking again you should see the pushrod deflect and know that its still sticking and needs more oil. If you see the pushrod flexing after a day or two of doing this just take the head off. Its going to be stuck worse than you will be able to fix with a can of MMO. Don

Bad fuel = bent push rods & broken rocker arms.

Whacky Macky has the rocker arm you need & if you get with me on the dimensions of your push rod.... I will give you one free.

Thanks for the help guys. I bought a bottle of Mystery Marvel Oil today and will give that a shot. My pushrod is still round and straight so I'm just needing that rocker arm. Merry Christmas!