Hi lucerne, you should have at least three, one on the range selector on the top, one on the change wheel cover, and one on the motor/belt cabinet door. I would urge that you do have them working for your own safety, as this is a fairly powerful machine, and you will get hurt if you get tangled up with it inadvertently, if you forget to stop it before opening any covers while it’s running.
Do you know the power output of your motor, as it really needs to be at least 1hp, but even with a 1hp motor, you won’t get the top speed, and probably not the next one down either. Not sure how the spindle lock button is fixed to the locking pin, so you may have to make one.
Regards Nick.