I have completed fitting the front seats to the rail supports and the seat locking levers. Found that to file the plastic sliding surface strips to be very difficult and also that careful measurement of the pin and holes for the locking lever is very important. I made the mistake of positioning and fixing in place the seat sliding rail supports before I had finished assembly of the front seat frame bases, and so when one base ended up slightly wider than the other, I had to trim back the sliding plastic and aluminium angle one one of the bases
I recommend full assembly of the front seat frames and bases before mounting the sliding support rails.
I can't imagine doing any of this work with the side skins in place, so think before blindly following the assembly manual!
