I am the owner of a Maho Mh700C with cnc control Philips 432-9 .

I recently blew up a driver card (lm/lm drive )while i was repairing a bad ridden optical reader wire. I had the card repaired locally and some op-amps were replaced with some supposed equivalents (old ops were UA714 , new ones are OP07) . The apparent fault on the screen was repaired but however i still have a fault on the y axis . when the machine is powered the table is stable . However once i put the hydraulic on the table starts to go down slowly on its own until it reaches the end limit . We have checked the inputs on the y axis drive motor and have found that the reference voltage on the driver (1trm3 ports E1A/E1B) is approximately equal to 0.3Vdc .
What should the value of the reference voltage be ? Can this be adjusted ? Are the replacement op-amps suitable for the card or are they causing this fault ?