Top Digital Powerful Lab Stirrer mixer 2000RPM 20L 10000mPas 110V

Assembled easily. One question. I'm having trouble switching to the high gear. I have followed the low to high instructions but it doesn't move at all in the position that should provide high speed. Any suggestions???

I bought this for a particular test where it needs to run continuously for two weeks at 1750 RPM. We're still getting set up but I ran some preliminary runs that went for 30 hours. It worked without any signs of trouble.Most overhead stirrers use a DC motor and control to vary the speed. This uses an induction (single speed) motor coupled through a variable belt drive to a reversible two speed final reduction. The dial on the front actually moves the motor back and forth instead of turning a potentiometer. The display measures the actual RPM. The speed varies slightly with load. At 1750, the speed would increase about 20 RPM as the various parts warmed up. We have one that has feedback, it costs more than $2000. This isn't a problem for us and won't be for the huge majority of users.The Jacobs style chuck accepts 10mm/3/8" shafts although the through hole in the head seems slightly smaller. The chuck looks like it's stainless steel or possibly plated. It also comes with a substantial steel stand, serviceable boss clamps, a padded beaker clamp about 100mm and a usable stirring paddle.Seems to be worth the money. I'll be both surprised and unhappy if it fails during our test.Yet another example of a seller that either doesn't know what their selling or can't be bothered to provide a decent description (in English). A good description will go a long way in convincing someone like me to risk the time and trouble to try out something like this. Deduct one star.