Ah, the famous Rega speed-change method:
1.) Lift the platter off the subplatter.
2.) Move the belt onto the larger section of the motor pulley.
3.) Replace platter and turn the motor back on.
You can now play records at 45 rpm speed. Repeat the process to switch back to 33rpm.
(And yes, this is in the manual. But it took all of 60 seconds to explain, so why not?)