The DC servo really isn't a feedback circuit. However, thinking about it, you do have the negative feedback in place, correct? Don't have the resistor numbers offhand, and I think the 2pf cap is compensation for the feedback circuit. 
  
You might just pull an active of each type, or if you have spares, test them. 
  
EDIT: R52/53 and 56/57 are the feedback circuit, with C1 and C3 as compensation caps (schematic shows 1pf).