How to keep medium film totally flat in a Nikon 8000 ed scanner

I've had one of these for more than a year and have used it extensively.
I've had some problems keeping medium format film flat.
I've discovered the trick.

First you must clean the rubberised tracks which grip the film. I use
alcohol on a Q tip. Do the upper and lower ones.
The film gripper has a lock so you can stretch the film flat.


The trick is when you lay the film on the track initially, run your finger
along its edge pressing it into its bed. This makes it stick a little until
you are finished. Then when you stretch it, it is dead flat.
I've had great success with this.
It is of couse not mentioned in any of the bumph with the scanner.