4k is an odd value - it's hard to find resistors with that value, so I suggest you check it with a multimeter. If it really is 4K instead of 4k7, I wouldn't expect it to make a significant difference to the operation of the circuit.
with the RS232 port connected to the PC and the Severino powered up, check the voltage on the non-ground side of C9. It should be around -10v. Then check the voltage on pin 2 of the RS232 port (= collector of T2). It should be between -10v and -6v.
connect the end of R5 that you lifted to ground. Check the voltages again. The non-ground side of C9 should still be around -10v or perhaps nearer -8v this time, but pin 2 of the RS232 port should be nearly +5v.
you have emitter and collector of the bc557 transposed