I have a single track Hornby level crossing, bog standard out of the box for manual operation, nothing which should be difficult. Unfortunately, the instructions and all the assembly videos I can find stop when you've put all the pieces together, not when you've got them on the track. Every time I try to put them on the track they either lift the track by about 2mm or the crossings tilt inwards. Maybe this is normal? Do the little tabs actually slot into anything or do you just place them on the layout? If so, where do you put them? I can't make it look anything like the box picture. Instructions do appear to be Hornby's downfall so far, even a beginner set appears to come with items with no directions as to what they are or how to use them. Can you help me out? Thanks.