Welcome Tink to the forums. You have found a great place for info, how to, and advice on Smart issues.
I also had shifting problems, and used these forums, and also the Evilution site to get everything sorted out.
Sounds to me like its either the shift actuator, or the shift motors. My 09 passion, has 84K miles, and was throwing
codes, occasionally would not go into gear, and one time locked up completely. So, use this forum, try all the
techniques, and you should end up with reliable, smooth and proper shifts.
If you have not already, get a code reader... that will help to identify the problem. Try to re-learn the tranny, very
easy to do, and will usually get you by as a temporary fix. Removing/Inspecting/Cleaning/Reinstalling the shift
actuator is not that hard. The Transmission shift motors is a bit more difficult, as you need to remove the air box
to gain access. If you get to that point... you may as well change the tranny fluid while the motors are removed.
Instead of reinstalling the air box, get a cold air intake tube, much easier to deal with, and I think the car runs
a little better with it.
Where are you located, how many miles on the car, are you mechanically inclined? Maybe I should have asked
these questions first?????