Air Filter

Replaced old with new,started right up.

Replace air filter.

Changed oil, filter and air filter and replaced trailing shield and installed new blade

Removed the filter cover,remove the foam filter and the filter cartridge and replaces them.
Removed the blade bolt, washer, accelerator blade and the main blade. Installed the new blade, the new accelerator blade, washer, then tightened the blade bolt.

Removed the air filter cover and removed the old filters
Installed the new filter and replace the cover
Remove the old spark plug and gapped the new one at 0.020

Self propel drive system failing,..belt guard deteriorated and rusted,...drive pulley encrusted with debris, causing belt to slip off. That issue caused me to think drive cable was faulty. Not true, I now have spare. Engine surging, and air filter in poor condition. Actually I adjusted the gov. spring and issue continued. Found governor at engine attachment point under engine housing very dirty and gummy preventing smooth operation,..cleaned with parts cleaner and inspected entire area,... reassembled and surge problem was gone without filter and foam replacement. Filter and foam replaced anyway. Kept old filter and foam after detail cleaning for spares. Replaced belt guard after complete cleaning. Drive system now operating as advertised. Additional and routine cleaning of enclosed belt housing will be necessary due to age and overall condition of mower deck blade area. Ordered parts I thought were needed prior to detailed troubleshooting as indicated here. Will continue to used old parts and now new spares are an immediate backup.
Very happy with parts availability for 16 year old walk behind, RWD , self propelled mower.