The Mergress and Merkur Progress are great shaving razors and those who own them love them. However, if you are a new owner of either of these two razors, you may become befuddled the first time you take the razor apart.
There are two things that you need to be aware of.
1) The spindle has a friction ring that prevents the knob from accidentally falling out of the handle. If you do remove the knob assembly for cleaning, you will need to pinch the two ends of the friction ring together while you slide the knob assembly back into the handle.
Make sure that the friction ring is in the recessed area and that it is not wedged onto the thicker part of the handle just below the adjustment numbers. If it is wedged, use your fingernail and twist the ring until you can push it into place. Once you have done this once, it will become clearer and much easier for the next time.
You can also remove the friction ring entirely if it bothers you. This will not affect the razor or shave but, you will have to be careful to not drop the knob assembly when unscrewing the knob from the handle.
2) The top cap has a notch on one side. Make sure that the notch is on the same side of the razor as the triangle on the base plate. If they are not lined up, the adjustment numbers will be off and it will not zero at zero.
I have a Mergress in my personal razor rotation and love it. I am confident that you will love it too as long as you follow these two pointers.