There are two hydronic toe kick heaters in Mom's kitchen, with a length of cast iron baseboard along the one wall.
Last year the bigger of the two units quit working. It was near the end of the heating season, and I just never found the time to dig into it. It's a real pain in the arse to get to, as well, as it requires lots of cabinet disassembly to get to.
I tackled the small one first. It just needed to be cleaned, as cat hair and dust gets sucked in and forms a mat across the back of the heating coil. Things were definitely not made for homes with pets. That one works nicely now.
The big one took a long time to get to, as I had to unload the cabinet and pull the floor, which still didn't give me access to the screws holding the cover on, or the motor.
Just on a whim I decided to bleed it in case that might be the issue -- I figured it was going to be a fail. Well I got a ton of air out of it before I got water, and when I tripped the thermostat, the unit kicked on. Even blowing well, so it doesn't need to be cleaned yet.
Win.