William, That makes sense. It would be awful light for leather. There is a large PA stamped on it but it is about worn off. It is a large stamp, unlike what I would normally associate with a patent #.
I worked as a Sears repairman for about 12 years and I never saw a Craftsman that looked like that. Would be a rare piece if it is a Sears. If the arm is all aluminum you may want to check how much flex it has. All the ones I worked on had steel in the arm making it very rigid.
There is probably a flame switch by your burner. With the cover off the switch may be triggered by your normal lighting. If the sensor is misaligned or dirty it could cause your problem.