My symptoms were the same. At first I noticed more and more noise caused by bearings going bad but it still worked. Then on a high speed spin the banging started. In my case the seal failed, which caused the bearing to start to fail, the along came the corrosion of the spider. I tried looking around everywhere to get just a new spider and no luck. The PN on the spider itself is 131450000. I phoned Sears (I'm in Canada) and asked about a warranty and they said they don't have Lifetime warranties on anything except hand tools so I was SOL. A new stainless drum and rear plastic drum would be $366, and just the rear drum with seal and bearings would be $255. They said they didn't sell just the stainless drum/spider but it appears others do.
So - I made my own spider with some 1.5" steel channel, a bit of round pipe and some 3/4" steel angle. The steel shaft does break out of the aluminium spider assembly with some effort and fit nicely into my round pipe. I put a bit of electrical tape around the shaft for a nice tight fit into the steel pipe which I cut about 2" long. I cut 3/4" angle iron into 3" pieces and drilled and tapped for M8 bolts (metric) to reuse the OEM bolts, which holds the existing spider, to thread into. I bolted the 3 of these into the drum and then also bolted these to the 1 1/2" channels (about 12" long). The other end of these channels got welded to the round pipe holding the shaft which was also welded into the pipe. I painted it and all works awesome. I took great care to make sure it was balanced and needed to put 2 washers under one of the channel arms where it was bolted to the angle iron.
After building and assembling it, I realized why the spider is not a separate part available to purchase (other than trying to get you to buy a new washer) - the reason I think is that when the stainless drum is bolted into the OEM spider, the bolts stretch the stainless drum around the bolt hole into the spider so removal without breaking it would be almost impossible - and so installing a new spider would also be very diffficult if not impossible because of the stainless drum material being pressed into the spider when the bolts get tightened. (Kind of dificult to describe but it you remove a bolt you will see the deformation of the stainless which kind of protrudes into the spider.)
Anyway - I'm happy so far with the new steel spider and have done about 5 washes - eventually with a high speed spin! I also installed a new seal and the 2 drum bearings. For my washer, the Seal is a TC 40x80x10 and the bearings are 6307 2RS and 6303 3RS. Pretty cheap on ******** or Aliexpress. My washer is a Canadian model PN 970-C41072-00 which I believe crosses to a 417-41052-00 but it appears that many use this drum assembly. My washer is indentical to the once shown in the video on this thread. This site has a great dissassemby video as does Youtube and it isn't too difficult if you want to give it a try. What have you got to lose - the washer is close to NFG if you are reading this anyway. If you have access to a welder and a grinder building your own isn't hard either - just take care to balance it so it rotates without wobbling although I really wonder how critical this is because many times the laundry makes the tub off balance too. Sorry - no pictures - I can't find anywhere to attach. Have a look on Youtube to see what others have built - that is where I got the confidence to build my own. Good luck.