There is still a possible reliability problem with this circuit.
Consider what happens when Q7 is turned on. The zener means that the minimum collector voltage on Q7 is 9V (24V supply minus 15V zener). There is no current limit for the collector current. I suggest a resistor in the collector lead of Q7, perhaps 680Ω. This will limit the collector current without harming the operation of the circuit.

bellow R31, from Q7's collector add 680R?

 

bellow R31, from Q7's collector add 680R?

Yes.

 

Yes.

thank you!
it works great