gallon of thinners , turn the comp upto about 130psi and use your sprag gun to blast every hole you can see , don't hold it in your hand , best done out doors , and make sure the wifes not got the washing out , this will move varnish but doubt this machine has had 4 star fuel , works for a good general clean mind , split the carbs as its not good for some rubber ..........".I had to drill out the float bowl choke tube" which part have you drilled out ?