"Unfortunately, my husband does not have a copy of this inspection."
Yeah, but I can't imagine how plaintiff goes about proving he messed up without producing it.
"He does not know what he wrote down for Heat on the inspection form. Are we a sinking ship?"
Can't know from here, but I highly doubt it. (Not sure why plaintiff is suing for $2500 in the first place.) Let's say he put down a recommendation that a HVAC professional look at it -- he's covered. If it had no apparent defect, he's almost certainly covered there to. Unless it *looked* bad and he didn't put something indicate it's status was questionable, he should be okay.
Still, it's a good reason to get better on the documentation/recordkeeping angle. I trust he also takes digital pictures of every inspection.
If he doesn't belong to ASHI or NAHI, he should look into that. They should be very helpful professional associations of which to be a member.