Pull off the carb and valve/rocker cover. Chances are you will bend up the cover taking it off, so a GSV series valve cover (cast aluminum vs stamped) will work fine as a replacement.

Spray the intake valve stem with carb cleaner through the intake port work it around from the rocker side. Some pull off the rocker and retainer to move the valve around. Eventually it will work free, give it a shot of lube on the stem and reassemble.

To prevent this, stop using old/varnished fuel. This effects the newer engines as the valve clearances have been tightened up for emission purposes. Starting to see B&S engines as well with the same problem (when they aren't dropping valve seats), but thats another story.

Most times it isn't even necessary to take anything apart other than popping off the airfilter. Spray through w/ the carb spray crank it over let it sit -repeat a couple of times and they usually function enough to run . Some follow through sprays once it is running a dab of Seafoam in the tank w/ some fresh gas goes along way. One poster was pulling his over w/the spark plug hooked up and hanging out of the block and found out that carb spray seems to be quite combustable....

thank you for quick reply: Depunisher and Tomplumb
i had valve retainer and spring off vice grips on stem still stuck. i didnt want to break anything.
after reading your posts and spraying thru intake and stem was able to turn and free valve, as you both predicted.
purchased new gas this year,and already cut lawn must of been crap left in 5 gal. can.
thanks jim.

Sprayed it,tapped it with a hammer lightly,and worked great! Thanks!

If you use about 1 oz/gal Marvel Mystery Oil in your fuel can all the time, you most likely would not be able to make a valve stick if you tried. For 2-cycles, 2 oz/gal in addition to the normal oil. Prevents stuck pistons from improper storage. All engines love MMO.

I stuck a valve in a B&S many years ago after doing a boneheaded stunt. I decided to put some alcohol I had in a can into the gas. It ran fine. The next day it wouldn't run at all but backfired. That's when it hit me - I had used the alcohol to clean a brush of shellac and put it back in the can! So I had to go get a fresh can of alcohol with which I treated the engine without disassembly and got rid of the shellac. That was sometime in the late '70s. The engine was still fine and had outlived several cheap decks by 1994 when I moved and gave it to my wife's cousin. As far as I know he still has it. :)