Part name and availability, of aluminum plate under brass, under armature?

Popped the flywheel off my 66 Johnson 40 HP Electric Seahorse (actually, w/ what was left of the sheared flywheel, it came off just by lifting).

Further digging, removing the armature plate, there is a brass plate. Under that brass plate, is an aluminum plate w/ 4 threaded holes and a rectangular large slot/keway (this plate is what the armature plate itself threads to).

My aluminum plate is cracked at the bolt holes, and is in three pieces (this no doubt affects things...and hopefully that's where the diagnosing stops)...any idea which may have happened first (key breaking, or plate breaking)?

What is this piece called...and is it likely to be available through a dealer (or is it too uncommon to likely be stocked)?

I have a printed manual, and the schematic that shows what I think is a similar looking piece, is #89...but that's on a blowup w/ the block's components)...unfortunately, I don't have a second page w/ the complete part name listing...and on the schematic w/ the flywheel and armature plate components, there is nothing else shown on that page that correlates to this piece.

Any help would be appreciated...I know, I'll check the manual back out from the library ASAP (I just never thought the last Evinrude would stop letting me down...but now it looks like I may be hooked w/ two...and trying to keep them running).

Re: Part name and availability, of aluminum plate under brass, under armature?

Part no. 303277, retainer ring. If that is broke, what does the outer edge's of the coils look like? Something had to be really hammering away. Plus, you had a sheared flywheel key. I would look farther here before going after part's.

Re: Part name and availability, of aluminum plate under brass, under armature?

When I removed the flywheel, it's obvious that someone was in there 15+ years ago, as there was only one coil (the other one was not there, but at least someone took enough care to replace the machine screws that would've held in in place...and the one coil there looks intact, and is not the old style potting).

What else would you suggest I try to do to ascertain the possible causes or extent of the damage (each piece I get at, I flop between whether this is the primary, or donor motor, and swap things off rather than on).

Thanks.

Re: Part name and availability, of aluminum plate under brass, under armature?

That retainer plate was used on literally tons of motors for about 30 years. There should be a lot of them laying around. I have a couple of them myself in my junk.

Re: Part name and availability, of aluminum plate under brass, under armature?

I did a pretty thorough visual inspection (not really knowing what else to check for).

But I am fairly sure that the driveshaft is perfectly straight (I supported a straight edge and ran the tip of that, to the top of the shaft, and spun things via the prop...no wobble at all there).

Good to know that part should be in a pile somewhere.

Everything else looks ok too...nothing scraped up, no shards of metal, no gouges...granted, anything could've been done since this was opened up and forgotten about (just hoping to get lucky twice w/ an old motor).

Even the coil that's in there looks undamaged.

Re: Part name and availability, of aluminum plate under brass, under armature?

Something broke that retainer, and sheared the flywheel key.high impact come's to mind. Such as, log,rock, bottom, or just no room for a boat,