Quite possible the bolt is a torx plus which is not the same as a standard torx.The sizes run exactly the same, T35,T40,T45,T47 etc.Because the outer edges on a torx plus are squared off, a standard torx bit in thesame size will fit but will feel sloppy.
Look at the outer points on the bolt closely,if they're squared off you need a torx plus socket.
TORX PLUS Drive System - Comparison - Camcar Screws from Acument Global Technologies
Quite possible the bolt is a torx plus which is not the same as a standard torx.
TORX PLUS Drive System - Comparison - Camcar Screws from Acument Global Technologies
a torx bit will scratch chrome by just being in the same room.
A tip on getting those torx loose, they can be a bear if they have not been touched in a few years and the scratch factor is very high when they do give. I use a snap-on 3/8 hand inpact driver, a torx bit will scratch chrome by just being in the same room, put the torx bit on the driver, give it one tap with a mallet no muss, no fuss, and most important no scratches, it's loose.
I like! I like!... keep those tips coming in Chopper!