It’s not clear what the LEDs are connected to, but it’s possible a screw in the barrier strip distributing the wall-socket voltage (“220 V” is definitely not USA-ian) has come loose and the input power to the supply is glitching.
The one in my machine looks like this:
Plenty of opportunity for a loose screw / ferrule / crimp, although it would not be a common problem. 
More new news: I lose the power supply bets. 
Apparently the “5AP” notation on the 36 V power supply apparently isn’t the “5 A peak” I expected. It seems to be a part identifier:
Find the sticker on that power supply with its ratings so we know what’s going on. If the sticker isn’t on the end with the terminal strip, then it’s on the bottom where you can’t see it. 
Assuming the input power distribution block (and all the wiring) passes inspection, that’s the supply to replace.
FWIW, having two low-voltage supplies (one with three outputs!) is exceedingly unusual. That’s far
more attention to detail than you’ll see in the current crop of imports.
Is that the:
Small, medium or black one?
As I see them:
The wires on the 36 V supply have tags 44 and 55, which match the wiring diagram, and those tags reappear at the stepper drivers.
I do not see any wires to the Ruida controller from what might be the 24 V terminals of the perforated silver supply. This could mean:
Can you get good pictures of the 5/12/24 V supply terminals and the power terminal block on the left side of the controller? Maybe trace the power wires from the controller while you have your head in there.
Wow you have been through a lot. I had a similar issue a while back. It turned out to be as simple as the lens had become loose in the holder. You’ve probably checked that already though.
I think you’re correct. No label visible without removing them. One on left with grill.
One on right with solid case
I read something somewhere that these are 36v and a failing one would have symptoms like lost steps and a red led flash as you stated. Could be a quick fix if its the issue. I’m going to try looking at it tomorrow whilst cutting and see if the red led illuminates.
So nothing connected to what the diagram shows as 24 V for the controller. That means the controller is (almost certainly) connected to the 36 V supply, contrary to the doc, unless something truly undocumented is going on.
Try to follow the controller power input wires to wherever they originate …
After a few days of tedious follow-the-evidence problem solving, that would be great.
I think there’s more wobbulation than a loose lens could account for, but it’s certainly worth (re)verifying the mirrors / laser head / lens all sit snug in their sockets. If anything moves when you (try to) wiggle / push it, that could be the problem.
Supposedly the Ruida can operate at this voltage, but it’s not recommended by the people who put out the specs.
This is from my 6442g Ruida controller manual.
Check out the last line..
My plan is cut the cat whilst monitoring the leds. Hopefully we will see something which indicates a power supply problem. I’ll remove it to see the label and go from there. Thanks again for your contributions they’re invaluable.
I see what you mean about the text being not level, and it looks like the dots have drifted a little also:
Here is a file that has a lot of rapid traversal movements:
test rapid.lbrn2 (126.5 KB)
To use this file, make sure Optimization is enabled with Order by Priority at the top of the order:
If this job triggers drift, what effect does increasing or decreasing accleration in Machine Settings have?
I’ll give anything a go right now. It’s been a painful week of testing and frustration. Something has changed in my machine but I’m sure it will show itself soon. I’ll try this test soon.
The small wobbles in the letters come free with a large CO₂ laser: you’re watching the laser head mount & gantry flex as the direction changes. Basically, you gotta get used to it, because there’s no real fix.
Small circles look badly (and consistently!) distorted, even though the wobbles are a fraction of a millimeter:
The big circle is 5 mm for an alignment post. The smaller ones are 2 mm and 1 mm, encoding the layer number in a layered paper design.
I don’t seem to remember them ever being so pronounced before. I don’t even think I saw them as a problem. I might be mistaken.
Unless you’re looking for trouble, you’ll never see them, particularly in larger figures. After you know they exist, of course, they cannot be unseen.
Not as I see it, because the two runs are mis-registered by a millimeter or two, which means Something Is Not Right.
Because the rectangles are engraved clockwise, alternating between 12 and 6 o’clock, I expected a single error would make the last few rectangles in the first pass (those left of 12) match up with the same ones in the second pass.
That is not the case: all of them appear equally offset.
If the cardboard shifted between the first and second passes, however, all the patterns would be offset as shown.
Run two passes again with fresh cardboard taped to the platform and see what happens.
