Yup, it's hard to tell the type of material of the foam grip from the picture but usually it is not pushed towards the end like the one in your picture.
It is usually NOT overlapping the plastic barrel nut.
If you have it, you can feel that it is a made out of a very high density medium-hard material, quite porous that it traps dust, dead skin and the likes. Run your nail across the grip lightly and you can see a white scratch. It is tightly coupled to the plastic handle and almost impossible to slide it around without enormous effort.
The clones I have seen are flimsy rubber grips. Some are okay but nothing come close to this genuine material.
I had access to a few 936s of different build year and the electrical cord is about +/- 0.05 5.00mm. This is where most clones get caught here. They are either 5.2mm or 4.8mm. Use a digital caliper to measure. If you have a genuine 936 with a different thickness cord please let me know because I only had 5 samples. I would like to hear from those who have the earlier units made in Japanese factory.
You can't judge real/imitation from the pictures, the seller might use a genuine item picture to advertise for clones that they sell. Asian ebay sellers are quite honest, you can ask them if it's genuine. Usually they will reply a no and convince you that it is same quality.