Seat sticks on monorail.
The monorail may not be clean or the bottom seat roller may be installed such that the seat fits too tightly on the monorail. Clean the monorail. Rollers often wear rapidly at first until they conform to the shape of the monorail. If this is the case, your seat may feel tight and your monorail may need more frequent cleaning until this wearing process is complete. If the seat is still very tight on the monorail, the bottom seat roller will need adjustment. See Seat Roller Installation.
Seat is wobbly.
The seat rollers may need adjustment. Adjust seat rollers as described in Seat Roller Installation.
Seat falls off the back of the monorail.
The seat carriage is on backwards. Remove the bottom seat roller, turn the seat around and reinstall the bottom seat roller. See the correct orientation as described in Seat Roller Installation.