On 10/02/2012 14:09, John Williamson wrote:
N_Cook wrote:

Could it be wear or dirt on the carriage or tracks, with the off centre
force from the spring making it wedge in position? As the problem is in
one direction only, I'd be suspecting a mechanical cause rather than
electonics failure, bearing in mind the tolerances involved.


That was my first thought but the first thing I did was to clean and
re-lubricate the tracks which didn't help. Also, as noted earlier when
powering up and finding the home position there is plenty of power. It
is only when returning from the scan that it is so easy to stop. Hence
N_Cook's suggestion about micro-stepping.