I didn't come back and thank you for the great information you all offered. Sorry for dragging up this old thread but it has been bugging me. I really valued your input and have put it to good use.

I got a new blade for the edger (another little wonder blade, since the salesperson wanted to sell me the same blade as i brought in) and have had no trouble ever since. I still have not serviced the engine. It kind of slid right down my list of things to do.

The edger works a treat. There is a groove that persists - just as described above. There might be better edgers out there but it sure beats attempting the same job with a whipper snipper. tired

Thanks once again.