Very hard to start. Will start with autostart and

Hello Sue; Has it ever been through a saw shop for tune up (at a good shop $40±, it includes some cleaning, new plug, new fuel filter, pressure/vacuum testing, carburetor adjustment, etc.)?
The coil is under the starter cover. You might check the gap with a business or index card.
Have you tried a new plug? much cheaper than a coil. Lou

If Sears sold this saw, then go to: searspartsdirect.com and enter the complete model number (minus the decimal point). This will bring up a series of drawings of all replaceable parts, part numbers, and prices. If you replace the coil assembly, use a thin business card between the flywheel magnets and the module to set the proper clearance. That spark needs to snappy and blue. Hope this helps!