Engine Did I Break Camshaft Gear or Lobe on Camshaft? HELP!

I am new to the Forum and have a very general 4 stroke engine question. I left 10% ethanol gas with fuel additive in my Troybilt Generator (Briggs and Stratton Engine 6.5 HP) way too long and the residue completely froze my fuel intake valve stem. I pulled on the starter cord several times and it was a lot harder to pull than I remembered from the past. I did remove the OHV cover and detect that the intake valve was frozen and not moving any, just the exhaust valve, when I pulled a few more times on the cord. The rocker arm and everything was just stationary on the intake side. Then I used some carburetor cleaner, penetrating oil to loosen the valve stem and it began operating up and down again when I pulled the cord. It appears that on the compression stroke that both valves are open part of the time and I think the timing of the valves opening has been totally altered. Is it possible that I broke one or some of those little plastic/nylon cogs that are part of the camshaft assembly for the intake valve? I think the intake valve was frozen closed and the rocker arm was frozen when it received the push from the steel rod to open the intake valve (compress the spring). It does look to me like something had to give when that rod could not push the rocker to compress the spring. Like I said, the question is very general and most any 4 cycle engine mechanic can tell me yes or no. Thanks for your input.

brownfox