Thanks for all the help and hints that you don't know you have given us!

Here's our question(s). We have a Craftsman power propelled lawn mower.
Bought in 1995. Only been run for maybe 3 hours tops. So everything still
even looks new. Took it out, cleaned it up, drained it, tightened it, etc.
But it won't start. Ordered a solid state ignition and put it in. Dave
thinks the problem may be a clearance problem but there are no
specifications in the owner's manual. This mower was from back when
everything Sears sold, had only Sears' name on it. So we don't know the
engine manufacturer. The mower is Sears model #: 917.376340 and the engine
Sears model #: 143.966500. This is 6.5 hp engine takes plug RJ19LM.

Dave is trying to find out the specification for clearance between the
magnet mounted on the flywheel and the solid state ignition. When the
clearance is set at 2 - 3 thousandths, the mower would not start. When the
clearance is set at 17 - 18 thousandths, it starts, runs rough and fouls the
plug. Of course, at this time, he isn't really sure this is the problem.
So if anyone has any other ideas, please?

Hope there is someone out there who can help with this. Even if just to
help us identify the engine, or if there is a standard for clearance that
might work?

Thanks again for all your help. We really appreciate the time it takes to
give it.

Judy