Small Engines (Lawn Mowers, etc.): craftsman tractor, safety switch, carbs

Question
I can start the 19.5 twin engine with choke , it'll run fine until I engage the blades , I can keep it running only by playing with the choke and throttle . I'm suspecting the safety switch . I could keep it from stalling by disengaging the blades but now that's not working, I have to depress the clutch as well. Carbs have been cleaned , I'm wondering if that engine has a history of bad switches.  

Answer
alot depends on this problem. if what your saying is starts, runs with choke off,  and as soon as you go to engage blades it wants to shut down??? yes safety switch down by mower engagement linkage is not working properly. if this unit sets out in weather, gets wet, theses switches get rusty inside and case trouble. i have found spraying wd40 into them from time to time helps. you will need to check into this switch.