Yes Peter, that is the positive crankcase ventilation valve, and it looks completely clean. The disc valve you can see through the hole, is supposed to be able to move back and forth as the pressure in the crankcase pulses. This is what the manual says:
If the fiber disc valve is stuck or binding, the breather cannot function properly and must be replaced. A .045" (1.1 mm) wire gauge should not enter the space between the fiber disc valve and body. (A spark plug wire gauge may be used.) Check as shown in Fig. 10. NOTE: The fiber disc valve is held in place by an internal bracket which will be distorted if pressure is applied to the fiber disc valve. Therefore, do not apply force when checking with wire gauge. Fig. 10 Checking Breather & Fig. 11 Breather Hose
