Re. the idea about inserting some magnetic shielding at the sticky point - the first knee jerk reaction most scientists will give you is that there isn't really any magnetic shielding material.  However - there are materials that magnetic flux much prefers to flow through, and therefore can be diverted away from an area.  Steel is obviously the best for this.

Moving steel into the path of a magnet is no problem - it will experience a force pulling it in.  But then you have to use force to remove it again.  In theory these forces are equal (that's always debateable when it comes to magnetic motors).  But basically the energy requirement should balance out to zero.  You could use a heavy flywheel to store and release the energy - or, you could have a balanced arrangement, where the force of the steel being pulled into the magnetic field is used to pull the steel away from another magnet.

Greendoor

I agree that in theory  the  forces are equal ...........however  theorys often  don't keep up  with  with  discoverys .

Wesley  GARY  descovered  a null  zone  in magnetic fields   many  years ago .........the   webpage I  listed  in my first post on this  thread   had an article  about  his  discovery dated 1879 .

Howard Johnson   spent  months  mapping   magnetic  fields and  also  found  the null  zone .   
Howard  Johnson wrote about  it  in his book  " The  Secret World of  Magnets ."   

A   piece  of iron  placed in the null  zone will take much  less energy to  move  than   a piece of iron  that is  simply close to the  null zone .      AND  the  piece  of iron  in the null zone will  compleatly  block the mgnetic field . 

Howard  Johnsons  book  was first  printed in 1970 .      As  far as I  know .......no one has  taken the time to  actually map  the magnetic field sense he  did it .    We have the  technology now to do it  much  better and  quicker ..........
I guess  we  all prefer    blindly  following theorys 


   gary

Trying to balance out one magnet moving a shield from another magnet and back is probably not a viable option since the strength of a magnetic field is nonlinear. It follows the inverse square law. But moving a shield from one magnet to another will work if the strength of the field remains constant during the transition. Look up Steorn's patent for a low energy actuator for a practical application of the principle. Its easier to build something that follows the laws of physics than defeat them.