The flywheel is the compressor pump’s pulley, which the belt attaches to and drives the crankshaft. Be sure the flywheel and motor/engine pulley is aligned, as a misaligned pulley and flywheel can damage the pump and motor/engine. Replace if cooling fins are missing. Most flywheels have a specific rotation (usually C.C.W. when looking directly at the flywheel) so be sure the flywheel is installed correctly when replacing it to efficiently cool the pump.
This item fits the following models:
3-Nailer Combo Kit w/ Accessories
3-Nailer Combo Kit
1/4" x 50 Ft Noodle Air Hose with Coupler and Plug