Transfer Fuel Gas Valve not following Reference

Dear CSA,
Referring to the subject, experiencing failure on hydraulically operated 4 inch Transfer GCV. Problem causes the machine trip during Lean Lean to Premix transfer...this happen always when the transfer GCV is closing.
Post the trip when valve is stroked , it works fine most of the time...have changed moog servos as a mitigation, however problem appears on multiple units here and there...

what is way of troubleshooting interms of control valve itself servo or the trip solenoid or else...
 
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