Could be 2 issues...

• First of all, what size are your bars ? The OEM bars are 22mm (0.866"), but a lot of the aftermarket bars are 7/8 inch (0.875") and there is a small, but significant size difference. On most bikes it doesn't make a difference due to the "clam shell" design for mounting levers and switches, but the BMW controls use the single pinch system which needs a very tight tolerance hole and bar. So if someone previously hammered on 7/8" bars, the hole in your controls could be stretched out.

• Item 13 sits in the crack on the inside of the "perch". As the 5mm screw tightens the perch up around the bar, the wedge is forced toward the center of the handlebar, acting to further tighten the grip the perch has on the bar. The only way to see if you have the wedge is to completely slide the perch off the bar. They are lost very easily, so it's easy to imagine your's aren't there.

Hope this helps.

Thank you for your reply.

I just measured my bars with a digital caliber, 21.97mm.

Ok, after taking the switch part off my perch I found a larger allen screw on the backside that holds the two perch sides together. Duh!

I don't know how I missed that. Maybe because everything back there is black, I had poor light, and my eyes are almost 70 years old! None the less, I found it, tightened it and the perch is holding tight on my handlebars. I believe it's screw, item #4. That's exactly what I was looking for.
At this point the perch is nice and tight, so I'm not going to pursue checking up on the possible missing wedge. I just replaced the switch part/cable of the perch and still have 7 or 8 wires to hook-up inside the headlight bucket. It's over a 100º in my garage! Arr, what a pain-in-da-butt. Got to love Las Vegas!

Thanks again...

• Those are correct 22mm bars then.

• Correct. There is a single, black SHCS from the front. It requires a 4mm Allen hex key. It's the same for both lever perches.

It was already 78°F this morning at 8am when my wife and I went for our exercise walk. The cows were already under the trees trying to cool off. It topped out today in the mid-90's here in green, rural Georgia. I'm having to take all my rides at 7am so I can be back by 9am. I agree, this is miserable.