To get a really satisfying feel to your scooter, nothing beats feeling the whole weight of it under your handlebars without any extra teetering. Giving it a slight wiggle front-to-back shouldn't produce any squeaking or rubbing sounds. Those sounds would be loose aluminum parts rubbing together. Again we address design shortcomings in four relatively easy points that I found eliminated all handlebar shaking or clunking noises on my M365.
Tighten the hook bolt
The first thing to check is always a loose locking hook. If your mechanism isn't tight enough, the whole thing will rock slightly front to back. That play puts excessive strain on the hook and will eventually crack it which is why it's so important to reinforce it before proceeding. Not only are these parts stronger, but they also prevent the mechanism from loosening as fast over time with regular use.
With the mechanism open, work through the following steps to make this adjustment:
Loosen but don't remove bolt going through the hook.
Loosen the two nuts inside the mechanism. These control the actual tightness of the hook. Move both inward or outward depending on how loose or tight the lever feels when you try to lock it.
Retighten the two nuts and tighten the outer bolt going through the hook.
Close the mechanism and try out the tightness. You want to feel a decent amount of resistance but not so much that you really have to put your arm into it.
Repeat the whole process until it feels just right.
Note that an improved hook initially needs some break-in, and light scraping of aluminum where it contacts the notch is normal. I found it's helpful to put some pressure on the lever while moving the stem up to lock it, before the hook makes contact. That avoids some of this rubbing and helps the hook get past that ridge so it locks cleanly. Otherwise, sometimes it doesn't make it which prevents the lever from completely closing.
Get a vibration dampener pad
These 3D printed plastic dampeners may seem gimmicky but they are in fact a necessity. They are pretty cheap, I would check eBay or other M365 independent stores. Double stick tape helps secure it and installation is plug 'n play.
Tighten the handlebars
There are two screws on each side where the head unit inserts into the stem which you used to mount the handlebars after unboxing. They tend to require periodic re-tightening. Unfortunately there can sometimes still be play even when tightened all the way, in which case a bolt coating product such as Threadlocker may firm it up.
Additionally, there are three screws fastening the actual bar to the head unit. Although they live behind the built-in headlight, they're easy to get to. The headlight has a screw on the top and bottom of it. Access the top screw by unsticking and temporarily removing the top plastic pane of the head unit's faceplate. The bottom screw is always exposed. Once removed, you can gently reorient the light to the side to access and tighten the three metric bolts underneath.
Put a bolt above the locking mechanism
Now, for the real project. This is the extra mile that really takes care of any and all remaining wobble or creaking. You've given enough love to the locking mechanism, but now it's time to look just above it. You'll find that the stem is slid into a post there and held by a steel pin on one side and a small screw on the other. It's also glued, but in my experience it doesn't last long.
It's really not the strongest design, and on top of that the pin continuously loosens itself out, jamming into ridges in the plastic lever collar (that black circular thing that keeps the lever in place) and preventing it from rotating free.
While the screw has a double purpose to secure the stem and to keep the lever collar in place, the pin on the other hand becomes useless with our new bolt. I suggest taking it out. I punched it into the hollow middle of the stem base which is big enough for it to drop out of the bottom. I used a punch around 3-5mm.
You could drill out the pin's hole, but that would require relocating the lever collar and redrilling a hole for its screw. So I decided to put the bolt just above that.
The usual disclaimer— this is as DIY as you can get and there are absolutely no guarantees about safety and stability. That said, this is tried 'n tested in the modding community, and has worked pretty fantastically for me. Proceed at your own risk.
I chose a black socket cap M6 x 50mm bolt and a nylon lock nut. I wanted the bolt head in the front as it looks better than a nut. On the other side, observe there is clearance for that nut between the lever and the stem when in the locked position.
To prepare to drill, I suggest eyeballing as close to the center as you can of the front of the stem and marking it. I measured the post at 44.5mm high from the top flat part of the upper half of the mechanism. The center of my hole ended up at 25mm from that flat part.
Put the lever collar's screw in as well to make it's lined up and the stem base is flush with the locking mechanism.
It's very important that you use the right bit size since any play in the bolt will just lead to creaking and wobbling again. If you went with an M6 bolt, use an M6 bit.
Carefully drill as straight and centered as you can completely through the stem. This creates holes on both sides of the hollow stem and the thick aluminum post under it.
That should smooth out all of the noises. Any more should just be a matter of the tightness of your locking mechanism or your new bolt.