We found all the staff at both Universal and Disney extremely helpful and couldn't do enough for us.
As far as I remember, the only ride we had a problem with was the Great Movie Ride at DHS, but other than that the rest of the rides were good. Obviously due to the tumours she couldn't ride the shaking rides like Earthquake so I cannot comment about those
On a closing note, I would very much like to praise all CM's and staff at Universal for their kind attention in looking after my Mum and for making her last holiday a one to remember x
Call Apple scooter, they will deliver the scooter to your hotel and it's half the price of the ones at the theme park. Plus, it's yours so it goes with you from theme park to theme park. At disney, if you want to switch parks you have to leave it and hope they have one at the park you are going to or you won't have one anymore. With this, you can just ride out to the monorail/bus/boat and take it to the other park or back to your hotel room. (It does make for a more cramped hotel room, though.)
I know there are other companies that deliver scooters, too, but I've never rented from them.