Engine mounting bolts were solid. HOWEVER, in the process of checking them and rotating the flywheel, I realized that there's a small metal piece attached to the engine block that has several tabs on it that interlock with the side of the flywheel housing when it's attached. I saw this piece moving ever so slightly as I turned the flywheel, but I couldn't figure out why based on the fact that the piece isn't attached to anything that moves. Then it hit me: as the magnets were going by on the flywheel, they pulled this piece closer. And a close inspection of the flywheel magnets showed tiny scrape marks where this piece has been pulled in close enough to make contact with the spinning flywheel. Smacking the piece with a screwdriver did reproduce a sound similar to what I'd been hearing. So when I get a chance, the next step will be to put everthing back together and see if bending that metal piece out a bit stops the noise. If not, I think the only thing left to do will be to drain the oil, pull the bottom off the motor, and examine the piston rod to see if maybe it's loose where it attaches to the crankshaft, although at this point I'm not sure how it could be since the piston seems to be operating as it should and there are no odd sounds when I spin the engine by hand. Thanks!

that whooshing/grinding noise is concerning. with new ovens, you'll oven get a lot of thumps, pings, and such, which, as cpovey noted, is just the metal expanding/contracting. you should be able to use your fan at whatever temp your oven is set at. the manual just says not to use the fan while using the broiler.

Can't say for sure without direct examination or comparison to the sound of the pump on Day 1, but from this position afar, I don't think there's a need to stop using the machine. The sound is very much similar to the pump on my Neptune TL and a friend's Neptune frontloader ... resonating of a pump motor mounted to bottom of the machine's cabinet ... but perhaps a little louder. Unlikely there's a start relay on the pump, they're typically a shaded-pole induction motor. Your choice to call for a service appt for your peace of mind and to confirm if there is/is not a problem. Myself, I'd keep using the machine as-is until the situation gets obviously worse (because it may not) ... as in the pump either leaking or going dead. Or better, I'd break into the machine and examine the pump for evidence of a problem ... but I'm a DIYer and you may not have the ability.

And now a follow-up to my March 8, 2017 post: after working flawlessly for ALMOST 3 years, the hammer had returned! Upon the advice of a plumber friend, I removed the arresters and shook whatever water that would come out of them out. I then reinstalled and they quieted things down for about 3 washer loads then the pounding started back up again. I came to the conclusion that the gas charge had failed which was verified by the customer service department at Sioux Chief. I was told to put a pencil, etc into the plunger hole and push - if I met with great resistance, the arrester was OK; if the pencil was able to move the plunger, the charge had been lost. My charge was indeed lost. Since the installation was less that 3 years ago, the warranty kicked in and a new set of 2 is to be mailed to me. I was then advised that because I have a newer, high efficiency washer to install 2 arresters per line to lessen the shock and extend their lives. Long story short, I purchased 2 new arresters and installed them; when the replacements arrive, I'll install them in tandem with the original 2. They had better last longer than 3 years - MUCH longer! BTW, Lowe's pricing has risen from $9.99 ea to $ 12.99 ea today!!