The furnace isn't humming this morning, and that's not a good thing.
Ooh, that's not good.
Been running around, making sandwiches, getting the boys off to school. About to check now...
My issue always seems to be the flame sensor. I clean it once a year with some sand paper to try to avoid it giving me problems.
I suspect it's a bigger issue. There was definitely water on the floor and this is what I see on the side of the boiler.

For those of you interested, service tech still hasn't shown up. I bought the house twenty years ago with this furnace and I suspect it probably needs replacing.
According to ChatGPT:
Boiler Unit Costs -
Standard models range from $2,300 to $7,000.
High-efficiency boilers cost between $3,500 and $12,000, with advanced features like condensing technology often increasing efficiency up to 95%
Labor Costs -
Labor fees for boiler installation typically range from $1,000 to $3,000. Additional work, such as updating gas lines or vents, can add $500 to $5,000
Total Replacement Cost -
On average, a new high-efficiency boiler installation for a home this size, including removal of the old unit, costs around $7,000 to $12,000. This includes the boiler, labor, and potential adjustments to the system.