Trying to freshen up my wiper motor.
I can't seem to get the bottom off.
Is all rusted and I would like to soak it in evapo rust.
Is the bottom supposed to be able to come off or should derust some other way?

 

Tim - That lower housing is STAKED to the blue colored metal/"magnet looking" part of the assembly. If you clean off the metal some up towards the upper edge of the housing you should be able to see 3-4 PAIRS of small stake marks in the housing. Sharp/small pairs of depressions.

As far as actual removal....I'll have to go take a look at a couple I have. I know one of the wiper motor restorers replates that lower housing so I assume they are able to remove and reinstall that part somehow. There is a captive bushing or bearing in the bottom/center of the inside of that housing....holds the end of the shaft and I assume has some grease/lube in it. Don't think that bushing/bearing is removable as it appears to be spot welded in place inside the housing.