Immergas EOLO Star 23 kW: Encountering Error 03 After Resolving Error 11, Fan Not Starting

There is no starting capacitor, don't combine just check/replace the relay.

Ordinary short-circuit coil motor, no starting capacitor.
Replace this relay.

Now I will throw in my 3 cents. An Eolo Star 24.3 cooker is working at my family's house. They called in a professional recommended by the cooperative on Friday, based on error 03 he concluded that the board to be replaced. By the way, he slightly devastated the cover of the isolated chamber (not the combustion chamber, just the outer cover, which separates the suction space from the kitchen) and then, aware of the demolition, he left without taking a penny, not even for the journey (long-distance).
By measuring with a meter and Macajew, I invented the cause in the form of a missing passage through the fan relay. I soldered two wires to the underside, which I manually shorted just after the pump started. Here a note of caution - you have to choose the moment of shorting experimentally, too late triggers error 11, too soon can't be either, because either 03 or 11. When I hit it, the furnace started. I heated up the hut, then extinguished the furnace, soldered the relay, cut the top off, cleaned the contacts and soldered it back on. On the third switch-on it caught correctly - this reassured me that it was the culprit. The board has been reassembled, tomorrow I'm replacing all three, apparently they recommend replacing the electrolytes too - I don't know if it's worth it, mine are nice, and you have to be careful with the board, one of the relay pads peeled off the laminate.

A video of the makeshift work:


After soldering, it remains to put the panel together, put on the already patched suction zone housing and the outer housing (this one is fine). What gasket do you recommend, it looks like some ordinary foam gasket, after the actions of the professional there is not much left on the lid.
Question #2: what are the knobs at the top marked "-" (above the tube from the pressure switch tee) and "+" (above the tube to the suction chamber, nothing is connected to it) for.
I wasn't turning, just asking out of curiosity.