Re: Will only start if the top 2 spark plugs are removed
The ignition on that model (and thousands of others) is self contained, meaning that it does not require battery voltage in order to be engaged. The voltage/power is supplied by the stator under the flywheel (round ring) BUT the engine must crank over at least 300 rpms in order for that stator to provide that power to the powerpack's capacitor.
Bottom line is that you must find and correct the reason for the slow cranking (electric starter) problem. Remove, clean and reinstall all riring/cables associated with the electric starter system.... this includes the actual battery terminals, solenoid connections, ground at the powerhead, etc, and be sure to clean not only the wire and cable terminal ends biut also the components they attach to. Tighten the connections with either a wrench or pliers... not your fingers if wing nuts are encountered.
The battery must be in tip top condition as must the battery cables. You can test the electric starter itself by simply running good known jumper cables directly to the starter.