It seems to be very dependent on the burr set, even beyond burr size

Congratulations on getting it running. Looks like a basic machine that out to last forever if you maintain and It's interestingly attractive. No idea what it is, but someone tried to differentiate it's looks from the more normal boring stainless box and I think it came out nice

I just got a Weber Key grinder. The recommended grind speed is about 70RPM. It takes about a minute to grind 16g. My previous grinder, a Baratza Sette 270Wi sounded like it ground at 10,000RPM. It would grind 16g in about 10 seconds. I'm gladly giving up that speed for the super quiet grinding of the Key. Its speed range

That is a control solenoid disconnect. It should have a screw going through it to keep it attached to the solenoid. Inside should look something like this: {image} If it has only 3 prongs ensure sure those 3 prongs mate up to the three prongs on your solenoid. Maybe you can find a wiring diagram and go through