I hope someone here can help me on this. After fighting my '67 repro mirror to get the bezel installed correctly, I now find that it won't stay adjusted to where I want it. Is there anything I can do to "tighten" up the cables or something? This mirror is driving me nuts

Where did you get your mirror? I got mine from CI, and it performed exactly the way you described--very frustrating. Eventually, after many attempts to get it to adjust properly, one of the cables broke free from the mirror plate where it was soldered together. It would then flop around and rattle incessantly. I can't see how to get the thing back apart to fix it either. So I eventually just fixed the mirror solidly to the housing. It's not adjustable now, but it doesn't rattle either. All in all I'd have to give that repro part a big thumbs down. I'm glad you asked this question. Hopefully, someone will have some good ideas about this.

Mine won't stay adjusted either. Everytime I shut the door "ding" goes the mirror out of adjustment. but it seems to stay fairly well if I'm not driving on to rough of road. I wish I knew the answer but I don't think I'm quite ready to glue it in permenent.

Yes, I got mine through CI on one of those 10% off deals. I kick myself everytime I fall for it. I had to send the first one back because there was a bare spot in the chrome the size of a nickel. My 10% savings turned into an added cost because CI never reimburses me for shipping. I've had this one too long to send back and already modified it to make the bezel fit. I will post some details of that, but basically I had to mill 0.22 - 0.23" off the back of the bezel and then make a special nut to back up the sheetmetal retainer. Now it mounts in the door correctly and has full adjustment but doesn't stay put.

I got some good advice from posting this question elsewhere. Gary (cammer-6) suggested I carefully crimp the ends of the sheaths and one of the Camaro guys suggested I tie a loose not with the cables. I already put another twist on the cables (think barber pole) and will try that first. All of these solutions will create drag on the cables. Hopefully one will work.

My Classic Ind remote mirror is hanging in there just fine. Never need to adjust it. Slam the door and it's right where I left it.

My factory mirror works fine, so I don't have to deal with it. I was hoping to see if I could pick up something on this one, but it seems that no one has a viable solution. Maybe a knot in the cable, but it it worked, you would have to secure it so it didn't slip with anything from goose tape to silicone.

As a last ditch, I might consider slightly kinking one of the cables to create a bind on the internal wire. As for the wear factor, once you have it set, and it doesn't travel, you shouldn't have to set it again. Once I set my remote on the last build in 87, I never set it again untill this last time I had the panel off.