I will not excactly recommend doing this at home, but here is something that might help you:
To align the doors, remove the back of the BS3000. In the top and bottom there are 4 screws holding the wire (2 each side). If the doors are closed, they will be pretty close to eachother. Do not screw them all the way out, just loosen them. Start with either top or bottom. Press the doors together as much as possible and make shure they are centered. Tighten the screws and move on to the other 4 screws. When looking good, connect to mains and open/close the doors. Now they might not close as pretty as you just made them, but then you have to do it again. You have to repeat this until the doors sit as close as possible and align nicely (though make shure the doores doesn't slam together when closening, some can do this).
If this not help your opening/closening problem i will suggest a good cleaning. Take a swab and some cleaning benzine and clean the tracks where the doors slide. This is often enough if its a little dusty. If this doesn't do the trick it is problably a worn out door motor or a worn out rubberring.
Hope this can help you 