remove gas from tank look for rust and remove tank if you need to remove hard deposits
remove lower bolt in the carb bowl and see if there is a discolor or white deposit on both carb and the bowl if so clean with carb cleaner both the bowl and center of the low part of the exposed carb.
remove oil and replace with 10w30
replace all filters and spark plug
Now put back the carb bowl careful not to damge gasket
Now once you have completed this add a 1/2 gallon to a gallon of fresh super fuel
Now leave it on the off position and pull cord 5-7 times , start pulling but nice and easy pulls to allow gas flow and lower in to be lubed
Now turn to start and try to start by spaying a little carb cleaner in the intake of the carb and pull to start
If it starts see if the rpm's jump up and down real fast , or it will run then die repeat steps 1-2
If it runs and let it run under a load, just plug a fan or a light and run to the unit runs out of gas
Leave tank empty and drain any fuel from the carb
ITS READy TO BE STORED UP
And to your question No you dont need any gasoline stabilizer because this how you store up all small engines of all types... if can learn to do this you will save time and money. I have a pressure washer, 2 generators 3 ATV and weeder for over 8 years now and I follow this each year and never had a problem
Or you can send it to a local dealer at 75.00 a hour plus parts and a back log up o 2 weeks 4951