Decided to test run my 4hp for first time since my ownership connected up remote tank primed with bulb pulled out knob on front which I think is choke? and pulled and pulled and pulled nowt! pushed this knob in and it fired up, let it cool down for several hours into tank again without knob and it fired up, I have not serviced it as yet, I can see through the cowl this knob appears to shut a flat (so must be choke)it last ran in Sep 05, Does this sound ok about the knob? I suppose every engine have all their own little differances on starting etc! thank for any help JBD