Here is a video for the 1200GTO. But this gives you a good idea of what to do.

I greased the RA gears on my Mach1GTO last weekend. It was very easy to do. The grease kit that AP sells has two different greases.  You can't use just any old grease. The grease kit from AP has VERY detailed instructions on how to take the motor box off, clean, grease, and reassemble the mount. I was very impressed.

The job took about 90 minutes to do the RA box, I suspect the DEC will take 30 minutes because now I know what I am doing.

Here are some photos. https://imgur.com/a/f2ab2pY

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Mach1GTO and GTOCP4 on permanent pier