In the last week our side by side occasionally starts to make a rumbling noise. When we turn the temperature switch to off for some minutes and then restart, the noise is gone and the unit normal running "hum" returns. I pulled the side by side away from the wall and found that our cleaning from the bottom front condenser coils at some time or another had torn some insulation near the bottom in such wise as to make a flap that the fan blades air flow could suck to itself enough to rub against.
After a thorough cleaning and repairing of the the insulation tear I have discovered that it is not that fan which is making the noise. The noise is coming from within/behind the back panel about chest high.

Q1, What is this intermittent rumbling noise trying to tell me needs fixed? (I see there are replacement evaporator fans for sale for this model that are located about where I think the noise is coming from.)

Q2, I noticed the end play of the shaft of that lower fan was more than 1/8" and closer to 3/16". A sort of spring clip that slides over the threads on the end of the shaft holds the fan blades on. I was unable to slide it closer to the motor by hand. Is that end play a problem? :rolleyes: I could not detect any wobble perpendicular to the shaft.:cool: Thank you in advance for wading through this "book"!

Seeing no way to remove the back panel I turned to the inside to remove the freezer contents and removed six sheet metal screws from a tall cover which exposed the culprit fan. Turning it off I could see it wobble as its rpm's spun down. It has terrible side play (or "runnout" if you prefer). I'm hoping that its replacement will be enough to extend the appliances useful life a couple more years or so.

I will keep posting progress in case there are any issues replacing the fan. It's time to get a part order underway.:)

:D With the aid of the AppliancePartsPros video (linked under the parts tab above with the picture of the fan) the change out was less than 15 minutes. It took longer to make a place for the frozen items that I had to move out of the way. The replacement evaporator fan was supplied with a wire harness adapter since it is used in many models, but this one didn't need it. All is well (I still am wondering about the shaft end play of the condenser fan).

Hope this experience helps sombody out there. Pass it on.:)

Oh , I forgot to refresh my screen and didn't see that Simon had sent me the very same advice. Thank you Simon!