I just had the plastic shaft on my CSR H-shifter snap off from its base.
I use with an X-CPO adapter mounted on 80/20 that is very secure.
You can see the setup on my Profile Page's album.
After it snapped off, I am able to see that it is identical to the Porsche shifter.
What Fanatec did was simply place a very heavy sleeve with an integrated shifter knob made of metal over the plastic shaft also used for the Porsche Shifter.
I had Porsche shifters before I purchased these CSR shifters, other than the shiny housing finish, and metal sleeve with metal shifter knob they appear identical.
I remember back when people were doing the mods to Fanatec Porsche Shifters by adding on after-market knobs with some kind of sleeve. I never went that route because I thought the added weight would put too much stress on the H-shifter's plastic shaft over time
Not such a big deal for the sequential shifter because the movement is much more limited than H-shifter. The CSR's metal sleeve and knob are much heavier than the after market knob I had considered putting on the Porsche shifter.
The CSR Shifter is only a few months old, so I will contact Fanatec tech support and hope for the best.
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Back to your question about the sequential vs H-shifter differences:
The Sequential shifter's housing is about 10mm narrower and 17mm lower than the H-shifter's.
The internal mechanisms are different, that is why the H-shifter's housing is larger.
They are not interchangeable because the plastic shafts on the H-shifter and sequential that support the shifter knobs have bases that are physically different.
