Polar 92 Knife dosent work after 1 hr of operation. Clamp Working

Please help!!
I have a polar cutting machine 92. The machine works fine for 1 hour but after that the clamp
works fine with both leg and buttons but the knife stops coming down. After about 20 mins of machine kept off it works again for 30 to 40 mins then gets stuck again. I am very confused what to do please help!!

 

Hi sir
Need the model of Polar 92 is CE or CS? O E, S, ED?
However can be a problem
1) Cam lever
or 2)Knife Upstroke control.

 

HI,
Thank you for your reply..

The model number is 90 CS

 

ok, please test the limit switch b22a +b22b ,and test it if there are ok electrical, clean very well + tight the wires.

see if the machines, has safety bolt, test it, if are working ok, and the limit switch is o.k, LUBE the solenoid with graphite very well. look if there are +42Vdc in the solenoid, and see if the card # 7B the small relais is working or contacts defective, or broken, replace it.

and adjust according with the Cam lever.

However, must test the power supply, in the card # 2+3+4 according with the schematic diagrams electrical, in Tolerance all Voltages from the Regulated Power supply.