Postscript...

I decided to keep the saw and guide rails for other reasons and I have just returned the FS90. Carbatec were super easy to deal with on this.

While I was talking to them in store; another CT team member said they had another customer report the same problem and returned their FS90 in the previous week.

FYI, this item is on sale at the moment from FT. Read into that what you will...