Some lawn mowers such as the Craftsman 37705 have a washout feature. It is essentially a garden hose fitting on top of the circular blade cover. This allows you to pump water into the blade assembly while running the engine. That action is designed to flush dirt and grass debris right out.
The Honda HRX217VKA is at or near the top of all of the expert best lawn mower lists including Popular Mechanics Top Ten Reviews and Lawn Mower Review. The testers at Consumer Reports gave this model top ratings for handling bagging and mulching and “very good” ratings for ease of use and side discharging. Additionally the reviewer estimated the breakage rate by the fourth year of ownership to be 16% which is well below any of the other mowers they tested.
To clean it first start with a cool engine. If your mower has a fuel valve switch it off. If you can disconnect the spark plug too. Next use a leaf blower to blast away any old dirt and major debris. Now gently lay the mower on its side fuel cap facing up. Try to get rid of any junk on the mowers underside as well.