467-3 Voltage detector repair

[Kyoungmin Kim]

Hello!!
I got a some problem with 467-3.
I tried to repair it, but I could not.
It operates normally at SV +/- 120mV and PV tests. But in SV 1 msec step the status lamp illuminated momentely.
As you know, it has to remain illuminate, but it did not.
I tried to repair this case, like change IC, resistor, TR, etc.
Somebody knows about this case, plz let me know why.....