Have a 3.5 HP, Briggs & Stratton Noma Brute lawn mower, model#: OMM6000, Serial#: 255025, Engine#: 90708, Type: 012801, Code: 8601100. Questions: Won't start with air filter on (replaced air filter) but if taken off~~starts right away, then, it won't start again. It sits for 1-2 hours and then the filter has to be pulled right off for it to start up again! Yes, everything else has been checked/replaced, what is the problem????? Please email me back, Bryan.