Latest update...

Did the most I could do and it seems to work!
Took the whole (almost) grinder apart.
Cleaned everything and removed probably a pound of coffee beans, bits and dust from all nooks and crannies with the grinder.
Cleaned the regulator worm and the main burr gear with alcohol to remove any unwanted lubricant.
Changed the burr set.
Ground down the regulator pin a bit to give it a better grab at the notches on the regulator frame. Although I believe that it is only there to provide a detent feel.

I did not think that I needed a burr change yet but I really wanted this last ditch effort to work so I went all out.

I ground a few shots and now the regulator knob does not move anymore...

I will give it a few days and see how it behaves and report back.

P.S:
Weighed the total grind retention of the K10 (with all removable beans taken out) with hopper usage
16.39 grams of ground or partially ground coffee that came out.
I was not very thorough at removing everything from the top of the burr so it is a generous number.

A double shot sacrificial grind should guarantee fresh cover in the next dose.

Also weighed the crusted over coffee cake. This is not coffee that I consider part of the normal flow, b8ut it is a data point that some may want to know.
2.68 grams of coffee ground crusted over.

Great news! Mystery solved...

The old adage holds true: "If you want something done right, do it yourself!"

Surprising the manufacturer could not give better recommendations though...

Thanks
Yes it is great news but I am not sure that the mystery is entirely solved.

I'll give it a few days before I'll call it a resolution and I am not sure if it was the thorough cleaning or the change of burr.

SpaceTime wrote:Surprising the manufacturer could not give better recommendations though...

Not if you have seen their videos

damonbowe wrote:Not if you have seen their videos

Cannot say that their video help me much... But for them it is publicity and they have to make it look simple and easy.

Whale wrote:Thanks
Yes it is great news but I am not sure that the mystery is entirely solved.

I'll give it a few days before I'll call it a resolution and I am not sure if it was the thorough cleaning or the change of burr.

My bet is on cleaning because reading your thread I was ready to suggest you to clean all "friction" areas - the area that needs friction to lock the the adjustment - from any oils. The fact that the part came to you bent because the previous owner tightened it to hard points that he had the same problem and most likely why he sold it.

It's like putting oil or grease on your car brake disks. You will not be able to stop. Your locking mechanism was slippery. Now it's dry.

LaDan wrote:It's like putting oil or grease on your car brake disks. You will not be able to stop. Your locking mechanism was slippery. Now it's dry.

True enough.
Yet changing the burr set probably reduce the resulting torque as well...

To me there is still a mystery here. Since the grinder is working now and I am a bit tired of taking the grinder apart, it may take a while before I get a real cause pinpointed...but the engineer in me will always want to know!

Well, I tell you what. Do a reverse engineering. Take that apart and apply some grease to the friction surfaces of the locking mechanism and see if the problem reintroduces its ugly face.

I double dare ya! lol