I decided not to replace the spin tube, or the tub support, simply cleaned it all up. New drive block, of course, which fit VERY tightly on the spin tube. Wire-brushed the centerpost, then treated it with a coat of POR-15 all the way up/onto the seal, but not past the seal onto the spin tube, and a few areas of minor rusting on rest of the support and pedestal base. DD bearings seem to last longer than BD, and (as I understand) a replacement tub support includes bearings preinstalled so replacing the support (if it comes to that) is more reasonable than dealing with pulling/setting bearings.
I did the same treatment to the Kenmore 90 about a year ago. Its centerpost had slightly more rusting than the Catalyst, and even some pitting. Did two coats of POR-15 on its centerpost and one coat on rest of the tub support and pedestal base.
Some here have reported that POR-15 doesn't last as long as one may expect ... which it is considered a primer that should be top-coated. Be interesting to see what's the condition of the Catalyst when it gets done with the first set of tenants ... or the condition of the Kenmore 90 after some use.
I have two more DDs to refurb (or three if my KA is included). One is a FreeCycle freebie Kenmore 400 circa 2006 that has a bad tranny. The other is a Roper RAX4232 circa 2002 that came from a deceased relative and was not used more than approx 1.5 years so should be in very good mechanical condition.
