Micromot 50 variants

I'm in the US and was able to get a Micromot 50 on Amazon.com. However, it looks like the model I got (Micromot 50/EF) has the variable speed control. I'm not entirely clear because the picture on the wiki shows a speed control knob on the unit. Hooking it up to a bench power supply at 15vdc, the speed control knob doesn't seem to do anything apart from turning it on. The unit also works from a PC switching power supply so I'm thinking this will work anyway, and using the fan PWM on the RAMPS 1.4 board seems to regulate the speed ok.

In hindsight I could have gotten it directly from proxxontools.com which is their US website and gotten the exact model for the same price. The only difference is that some models have the keyless chuck (good) and others have the speed regulator (don't really want).

The other thing I forgot to add here is that I have not yet been able to get the Micromot 50/EF fully disassembled. The toothed threaded ring that holds part of the cover in place seems to be embedded in the cover. I've tried filing part of the cover down a bit to expose more and it keeps going down. I gave up after filing down 1mm.

That part will not turn without cutting more of the polyamide housing.

I should be able to work with it as-is but I thought I'd mention this in case it's a more recent variation in the basic housing.