Never, ever turn speed handle without motor running. NEVER!
All sorts of internal damage can be caused. You can strip the gears on the speed control handle, bend the speed control worm gear, strip teeth on the quadrant, pull the control sheave bearing out, bind the drive belt, break the casting where the speed control mounts, strip out speed control mount holes. All will cost you extra money in repairs.
Oil your control sheave and motor sheave every 5 hours of use, or every 3 months if the machine is just sitting there. The oil can dry up and make the sheaves stuck in position and the machine won’t change speeds after that.
Be sure your motor is grounded to a 3 prong wall outlet so you are safe from shock. Whether it is grounded or not, use a rubber mat to stand on especially if operating it on the ground or on a concrete slab, for extra security.
Try to keep your machine and environment sawdust free. The machine will last longer and require fewer repairs, but more importantly is your lung health and even your skin health. Sawdust fibers clog up your lungs. And there are toxic woods which irritate the lungs, throat, eyes and skin. So use dust collection at the source of the wooddust, and vacuum off your machine and working surfaces, the floor, and vacuum out the headstock from time to time as well.
Unplug your machine whenever you are inspecting inside the headstock, and unplug it when you are making tool changes to prevent accidental activation. Don’t use floor foot activated switches, they can be accidentally stepped on, or something falling on it could activate your machine.
Read, heed and understand your owners manuals for all tools. Don’t get hurt!
Be careful with electricity! A funny video from an electrical engineer who should know better.