Pearl need help

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I clone a Pearl phono stage a year ago( PC board order from Pass-Labs), all check point voltage was correct and good performance. since I stop use it 6 months, today it is out of working-right chanel no sound and left chanel have very small sound. I open the cover and measure the check points voltage. the Q5 - Q8,Q9,Q10,Q11 point voltage before is 10.75V now only 1.80V (both chanel same), R18 - R21 point before 11.52V now 2.23V, R23 point was 15.11V now 2.45V. Looks like R19 has a lot voltage drop. I have changed Q5 than changed Q8,Q9,Q10,and Q11 but have same result. I don't know how to check the 2SK170's quality, I need help please give your advice.Thank you!
BTW other check points voltage are correct.
 
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