Hi Mike,
Does it look like any of the three engines in my last post? The one on the left is a saw engine. The one in the middle is a standard trimmer engine. The one on the right is a Roadrunner trimmer with a Echo style engine. It is hard to answer questions without knowing what you have or exactly what you are describing. You may have an old engine with points. Engines produced in the last few years just have a flywheel and coil. The flywheel is keyed to the shaft and the coil is mounted in a fixed position above the flywheel. All you di is set the clearance between the coil and flywheel. Since you do have internet access, just do some searching for McCulloch on the net. When you find a picture of an engine that looks like yours, save the picture to your harddrive. You can upload it in a post so we can see what you have.

Dave