[softic]

good note about grounding - will do it this time.
actually I have checked resistance between pins 1 and 2 last time after soldering a new transistor - it was okay... can it be because of too big current?
I estimate the current through the transistor should be no more than 1A (assuming we have 14V on it and 16Ohm load on solenoid).

so I will solder a new transistor this evening and will check the result.