What routine maintenance intervals should I follow for the welding generator?

The manual specifies maintenance at intervals of 20 hours, 50 hours, 100 hours, 200 hours, 500 hours, and 1,000 hours, and instructs owners to stop the engine before performing any maintenance. The engine should be serviced more often during severe operating conditions. Cracked cables should be repaired or replaced as part of routine upkeep. (Page 13)