Thanks to everyone's suggestions, I have put in a new fuel filter, drained and replaced the gas, changed the oil, put in a new battery and air filter and oil filter. Sears Lawn Tractor 917.273130 still won't start. I cannot find where the spark plug is located. I have a new one, but can't install it. Does anyone out there have a suggestion?

The engine "clicks" when I try to start it, but will not turn over. Is there anything else that I can do without a service call?

Thanks to everyone for your help. Sears owner manual seems to assume that everyone knows how to change spark plugs, and filters, so there is no detailed information beyond "change the spark plug". I find it in the schematic, but can't figure out what I'm looking at.

Look at Parts & Accessories | Shop & Find Lawn & Garden, Appliance Parts at Sears Parts Direct | SearsPartsDirect.com from Sears (http://www.searspartsdirect.com) They should have a nice diagram.

Look at item #5 on the link below. It's on that side of the engine.

http://www.searspartsdirect.com/partsdirect/retrieveSubComponentPartsAction.action?diagramPage Id=00006&componentDescription=CRANKCASE&documentId=P0301010&modelNumber=CV490-27508&productCategoryId=1503500&brandId=0598&modelName=ENGINE&backToLink=Return%20to%20Sub%20Components#diagram

How did I get there. Went to searspartsdirect. Typed in model. Found engine #. Typed in engine #. Went searching. Yep, the plug is in thin air.

So, just look somewhere on the left side of the diagram, just above the big bored hole. That's where the piston goes. The plug is right above the piston.

Look around the front of the engine, or just back from the front on each side. There will be a black wire with a rubber boot at the end that goes to the spark plug.

Thank you Mowerman2468 and Keepitsimplestupid! YOu guys rock!