If the pilot is going out, after the main burners have been on for a while...
Look to see if the cold junction of the thermocouple is resting against the bottom reflecter plate of the boiler. (Causes the thermocouple dcmv to drop)
Watch to see if the draft being drawn into the boiler is pulling the pilot flame off the thermocouple. (the pilot flame is too soft)
Watch to see if any of the flame on the main burners is floating just above those burners. (The heat exchanger needs cleaning or the unit is overfired)
Then it's thermocoupler testing 101
That technician should put an adapter in between the thermocouple and the gas valve to do a real time dcmv reading while the boiler is at rest and when it's firing.
When the burners are not firing, you need the normal closed thermocoupler dcmv reading and the time & dcmv output it takes for the pilot solinoid to drop out when the pilot is extinguished to see what the problem really is.
Then the reading of the thermocoupler output when the burners are firing. (for at least the length of time it was taking the pilot light to fail.
This will tell you if the pilot outages are from the thermocouple/ thermocouple pilot solinoid/or boiler conditions.