Keratoconic

Any advice on fitting the cab floor to the cab? I'm finding the fit too tight at the front, it needs to go another 5mm forward, but there is an obstruction I can't find, the floor won't go low enough as if the dash is catching on something. Unfortunately me or my daughter can't get fingers in far enough to push down on the floor and the plastic is too fragile as we can feel it start to give, so in danger of breaking something if it is forced. Thanks GB