You see my theory was that I might have loosened too much and the blade wiggled while running and caught the inside of the deck and then broke something up in the engine. The bolt and key seemed secure enough when I checked after this happened but it's a different story when a motor is running at high speed. It IS the right size blade but last season when I installed a blade it was cutting into the plastic lid that covers the side grass discharge. So when I pull the cord the blade still spins but it sounds like something is loose in the engine. And it makes a weird reving/grinding noise. Based on my problem I was hoping someone would give me ideas to what's broken to see if it is worth fixing.

UPDATE: The sillcock key did the trick. It was a 4-way cross configuration, with 1/4", 9/32", 5/16" and 11/32" square sockets. I tapped out the cross piece, to give me two tubular sockets, and found the 5/16 size would fit over the set screws. I was then able to place a piece of square section rod in the other end, and used a wrench to get the set screws out. They were not that tight, which makes sense with the alloy pulley they were tapped into. With some prying, I was able to get the pulley off, pull out the impeller shaft (woodruff key fell out with pulley), and remove the bearing assembly. The bearing itself, does not look to bad. I measured the internal diameter and the impeller shaft diameter, and have less than 1/32" of play (far less than the 1/8" Tomplum mentioned). I am still puzzled by the hex set screw in the bearing housing. The brass sleeve runs through the center of a ball, formed by two pressed steel hemispheres. This ball is retained by collars on the impeller housing, and can rotate to compensate for variations in position of the front auger gearbox. The set screw is in the overlap area of the two steel hemispheres, so it may simply be providing additional securing for holding the pieces together. I was also wondering if the assembly contained some sort lubricant, that was intended to permeate out and lubricate the bearing? Anyway, I was intending to check the front auger end bearings next, and then reassemble. I was thinking that some sort of lubricant would be beneficial on the support bearing. Normally, I would expect to use oil on a sleeve bearing but perhaps this application is different? It certainly wouldn't be too difficult to occasionally add a few drops of oil to the shaft on the pulley side of the bearing. I am open to your opinions and suggestions, based on your personal experience and knowledge. Thanks again for all the responses.

It's perfectly normal. The gurrgling is the RO system generating a storage of water. It takes something like 4 gallons of water to make 1 gallon of RO water. The gurggling is the extra water running down the drain, it needs to do this to flush the membrane filter. The expansion tank is where the RO water is stored. Take Care Dan Martyn

Dishwashers don't "pull" in water. Thy have a solenoid valve that opens the line and fills the basin. Once filled the pump inside turns on and pushes the water through the sprayers for the wash cycle. It drains and repeats with fresh water for the rinse cycle, just like a clothes washer. How do you fill the dishwasher? Often the dishes will bang when the pump/sprayers are working. The only way I can see the kitchen tap coming into play is if you have a solenoid issue as suggested by ionized. It could be cycling open and closed and the noise is water hammer as it opens/closes. Opening the tap would reduce the line pressure and lesses the resulting water hammer as the valve opens and closes.