cold cathode gauge was really dirty! It was cleaned(see the picture)and put back. Still the system was not pumping down ok. Diffusion pump (IVC/OVC) was dirty too. It was dirty and full of junks. All the parts were taken out and got cleaned. O rings were replaced. Valves numbers 35,36,27, and 28 were disassembled and IVC cold cathode gauge was in a bad shape. It was cleaned and an angle VAT valve was added.
System assembled back together and pump down was ok.