Orientation of parts - Be sure to check and re-check orientation of blue and gray connectors. If you are unclear of the orientation on one page, go to next page to see what hooks into the pieces in question - this will help you place them correctly.
Track pieces - Connectors should attach to the track pieces with a firm snap. This will happen each time if you are sure to have each track piece oriented as the page clearly shows before attaching the connectors. If your track pieces keep popping off after you have attached them to the main structure, it is likely you have not "snapped" the connectors onto the correct side of the track.
Chain - Your chain may occasionally get caught on the black Chain Guides. When this happens the chain will stop moving and you will hear the motor clicking. Simply re-position the Chain between the Guides to stop the problem. Also, be sure to count and make sure you have the appropriate number of chain links put together. You may actually get a piece or two more included in the bag than what is called for in the instructions!
Specific Building Help
Page 7 Difficult connection from purple rod to purple connector
Page 14, Step 13 Pay attention to angles of connections
Page 22, Step 24 There will be a space between the Silver Spacer and Orange connector on the Red Rod that is not shown in the instructions
Page 36, Step 51 Track piece being connected should be attaching over the structure not under as shown in the picture.
If the coaster car is getting stuck at the top of the hill before it drops off the purple connector can be disconnected