Modig md 5000 TNC 155P Emergency stop defective

Hi . i`m new in CNC bussiness . I`ve bought an milling machine . more precisely : Modig md 5000 with an HH TNC 155P controller. My problem is this error " Emergency stop defective " . In the manuals it says : "-Fault in the emercency stop circuit of the machine (for checking routine see Mounting instructions and Interface Circuit Control-Machine manual TNC 155 A/TNC 155P) ; -Defect in Control`s internal Emergency Stop supervision " . Since i`m just a student , i dont know where to check and solve the problem . I cant find that Mounting Instructions and Interface Circuit Control-Machine manual . Is there an online version ? or someone who had this type of TNC can help me ? What i know surely , is that the emergency stop knob is broken . but it worked fine 1-2 weeks without any alarm . now the machine is keep blocking my commands because this alarm . if i change that knob , it should solve the problem ?

Thank you and have a nice day !

PS : i know my english is a little bad , and maybe i`ve just made a mistake buying an old cnc . but it was at good price , and i want to learn and work on cnc milling machines .