ORIGINAL: DaveB
before you get too deep in theory, take a look at the bolts holding the engine mount to the firewall and the bolts holding the engine to the mount. If the firewall bolts have loosened, the plane will pull to the right big time on take off. It's worth a look.
DaveB
Thank you all for the replies. DaveB I will check the bolts as I haven't checked them in a few weeks.
Much appreciated