Mark wrote:
yes the blower is before the heat exchanger

also so that the heat exchanger is under positive pressure...

if the heat exchanger cracks the distribution air will be forced into
the combustion air and not the other way rond which would be much more
dangerous...

http://www.bacharach-training.com/Tips/Tips.htm

Mark

Yeah, that was kind of my hunch.
There was a puddle of oil in the bottom under the burner, and I was
thinking the air leaking from the exchanger maybe blew it away from the
burner.