I haven't been checking the sleds like I used to - well I didn't need to, they work. I should have clued in though when LL said they'd be restarting the sims ..... but I didn't until one of my visitors sent me a message. You see when the island is restarted, by me or LL - the sled script adds another copy of the sled to the start area. This is problematic because when somebody sits on one the other one bumps it in the air. So, I have to go around and delete both of the sleds and then restart the script. Once I do that everything is fine - unless the island gets restarted again.
It's not the fault of the script - it's just a side effect of the restart.
So my apologies to everybody that had trouble with the sleds since the restart. They're fixed now. :)