Yes, I set the scale as deep as it will go and, it does seem to be the exact same place the Fast Fix stops the blade at, so I think Guy may be right.
I bought the saw from Screwfix and got a shock when I opened the systainer. It was a very disappointing sight. It looked as if the saw had been unceremoniously "dumped" upside down in the systainer with apparently no packing whatsoever to protect it. Having never owned a Festool product, I didn't know if this is how they are usually shipped. The Fast Fix lever is very slightly damaged, has a black smudge on it and smudge marks on the casing and the manual.
I wrote to Festool and they said that I'd be entitled to take the saw back to Screwfix for a replacement or they could offer me
£100 worth of accessories. So, I said that, since the damage seemed merely cosmetic I would be content to keep it.
At that point, I hadn't even used the saw and, it was only today, a week after I picked it up that I tried to cut the 25mm MDF and the blade wouldn't go past 25mm but of course, I'd need a cut of at least 33mm to take into account rail + board + 2mm, wouldn't I ?
Anyway, I imagine I'll need to send Festool another email and maybe end up getting a replacement.