To prevent the build-up of “muck” in your ducting, here is a simple and easy way of keeping the ducting clean.  First remove the waste bucket, emptying and wipe clean.  Next, get about 1 kg of rice and place it in a bowl.  Go to the inlet the greatest distance from your power unit.  With your hose, suck up the rice and let the unit run for a short time.  Next, empty the rice from the waste bucket, remove any foreign matter if possible, and repeat this process for every inlet.  This process has the effect of “sandblasting” your ducting and removes any build-up of “muck” that may cause potential blockages inside your ducting if left unattended.