properly attach the side mirror glass?

[McSam]

(2015 3.8)
I repaired a busted RH side mirror glass with a Burco fit-over but cannot replace it securely. It pops in OK, it's stable through all rotations and fold-in/fold-out, but after a day or two it pops right off with a loud bang and dangles by the wires, seemingly on its own but more likely while rotating or folding [[??maybe as the seat memory adjusts for the final exit position??]].
I'm wondering if the 2 metal prongs (marked with purple circles) need to be adjusted. Otherwise I can't see what is actually holding it in place. I'm also thinking now that the round actuator should be attached to the mirror backing and not to the mirror housing. How would I accomplish that and then re-attach?
See 2 photos:
Thank you very much!

 

[enrique_7812x]

The round part of the mirror backing is only friction-fit over the round actuator, so my first guess is yours is not pushed in all the way for a snug fit, or a wire or debris is in between the two parts? Hard to tell if it's just the angle of the two pics, but the two prongs do appear to be pushed out a bit farther in the "clean" OEM backing version. Not sure if that would make any difference. In the bottom pic, there are two white plastic pieces on the right side of the actuator (one looks like an arrow). Are these supposed to align with something on the mirror backing?

It's only a generic video and probably won't help much, but here's one from O'Reilly's.

 

[McSam]

The round part of the mirror backing is only friction-fit over the round actuator, so my first guess is yours is not pushed in all the way for a snug fit, or a wire or debris is in between?

Here's another picture in the "popped" state:



Note the 4 compass point plastic tabs on the actuator (only 3 are visible). They probably fit into corresponding notches in the mirror back which needs to rotate. Since the mirror cannot rotate, the actuator must do so before attachment to the housing. I could probably unscrew the two parts, but how would I re-attach the actuator once locked into the mirror?
I do think that it's pushed in all the way if only judging by the smooth omnidirectional response to the motor's motion, but also by the way it feels when I pop it on; any more pushing seems ill-advised.
While there's also nothing between the two parts, the Burco fit-over does add a 1/4 inch or so to the thickness. Could that be a factor?
Let's continue...

Hard to tell if it's just the angle of the two pics, but the two prongs do appear to be pushed out a bit farther in the "clean" OEM backing version. Not sure if that would make any difference.

I do think it's just the picture angle. Those two prongs are quite stiff and hard to bend. The fact that the housing is folded in, and also my memory of a similar prior event, almost confirms that the problem is now limited to the mirror movement for the final exit position. Maybe the combination of motor and housing motions is stretching the attachment limit...

In the bottom pic, there are two white plastic pieces on the right side of the actuator (one looks like an arrow). Are these supposed to align with something on the mirror backing?

As noted, the 4 points are probably involved with alignment. The two white plastic pieces depress easily into the actuator, as if they were signaling devices or something.

I seem to be closing in on a solution but still need help.
Thanks in advance.

 

[McSam]

OK I'm back, having wiped off some egg from my face. Enrique was correct, there was blockage between the 2 parts. It was visible in hindsight in my original pics, but this yellow arrow shows it clearly:


The grey wire harness belongs in its bracket to the left, otherwise it sits in the way of the folding assembly, causing the mirror to pop off. I was also misremembering those 2 white "arrow" thingies on the actuator. They are firm and don't depress into the actuator. Still don't know what they do, though.
Meanwhile as I was fumbling with detaching and attaching everything, I broke off one of the 2 narrow mirror connectors circled in purple. Hasn't affected any of the movements, but I wonder what function(s) I've now lost. Defrost? Blind spot indicator?

 

[enrique_7812x]

Sounds like you got it back on and working for the most part, so congrats! What a PITA. It shouldn't take you much to figure out what you've lost with that broken connector, and it seems like it's fixable fortunately (another day maybe). Good luck if you go that route. At least you know what to look for now. Thanks for sharing, it helps guys like me learn over your shoulder.