anyone have this or similar TOMY Thomas set

Littlejen22

Thomas Mail Delivery Big Loader.  Do the plastic trains just sit on the train part or do they snap together or something so that they actually stay together when they go down the ramps?  Ugh, my Aunt is one of those people, and I love her but, she is always giving CRAP to the kids and she gave DS this set and it is missing a piece of track and I have no idea how to get the trains to work.  But of course DS wants to play with this instead of his awesome wooden set!  So even if I figure it out we are still missing a piece!  I guess it could be worse, at least it is clean unlike the nasty wooden blocks she gave him the same day.