Van Dorn 320 HT series with Pathfinder 1000 control thermocouple break alarm.

HI
Thanks for approving me.

We have a van Dorn 320 Ht series with pathfinder 1000 control unit. Upon startup after being turned off all the way at the end of the previous day It will throw a thermocouple break alarm within 15 minutes of being turned on. It will either say nozzle zone thermocouple break or center zone thermocouple break or rear zone thermocouple break. Take your pick. it's random which zone it will complain about. I will hit the alarm button on the control panel to silence the alarm only for it to go off again 5 seconds later and again hit the silence button and it goes off again 5 seconds later and the only way to clear the alarm is to turn the machine off then back on and repeat till it stops complaining. I looked in the owners manual we have for the unit and it doesn't say anything about thermocouple alarms. I know the pathfinder unit is shot as the screen is impossible to read and there's lines and a green splotch that seams to grow each time the unit is turned on. Could these be false alarms due to a failing control unit or what should I check? Like said it's random as to which zone it will complain about on start up. The machine I believe is from the early to mid 90's. The company I work for makes hydraulic seals,gaskets etc.